Nov, 18 2016 | Written by ATLien Another day, another court loss for Sheree Whitfield of The Real Housewives of Atlanta. [FLASHBACK: Sheree Whitfield Loses Court Battle Against Bloggers... ] As you know, Whitfield is now a cast regular on the popular reality show and she's apparently been doing anything to hold on to her peach... including breaking the law! The court savvy home construction professional now faces fines after she held her 'housewarming' celebration for her 6 year project without proper permits. Details below... Continue Reading... Nov, 18 soho15.org 2016 | Written by ATLien Welp... it looks like Nick Gordon will be http://www.tcpglobal.com/Auto-Body/Dent-Repair/ forever dodging the repo man now that the Brown/Houston family has won a multi million dollar judgement against him. If you recall, last September Gordon was found legally responsible for the death of Bobbi Kristina Brown after he failed to respond to the civil suit filed by her estate (click HERE if you missed that). Now, a judge has determined damages in the case and Nick has been ordered to pay his former flame's estate over $36 MILLION DOLLARS and while Bobby Brown probably knows Gordon doesn't have it, he's happy that at least Nick won't be able to profit from Bobbi Kristina's name. Details below... Continue Reading... Nov, 18 2016 | Written by ATLien Another day, another Kanye West rant goes viral. This time, it's Kanye's views on Donald Trump that has set social media ablaze. Last night the superstar rapper shocked fans and supporters during his Saint Pablo tour in San Jose, when he decided to share a moment of honesty about his voting choice, declaring: "If I would have voted... I would have voted on Trump". Details + video below... Continue Reading... Nov, 17 2016 | Written by ATLien Newsflash! Joseline Hernandez of Love and Hip Hop Atlanta is still pregnant. While the father of the reality star's unborn child remains a mystery, Joseline has filed court documents indicating that it's Stevie J. and she wants him to take a paternity test and provide support. But the real tea is that many don't even believe Hernandez is pregnant, especially since it's been often rumored that she was born a man. [Disclaimer: This is an open post. This post will not be censored or moderated. Disqus may automatically moderate certain words considered offensive. There are no rules in 'Open Posts' so enter at your own risk.] Continue Reading...
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Average Cost for Dent Repair Dent Size in Diameter Cost 1" dent $75 - $100 1" - 1½" dent $100 - $125 1½ - 2" dent $125 - $150 2" - 2½" dent $150 - $175 2½" - 3" dent $175 - $200 The procedure to repair a dent is actually quite simple and you can do it yourself, if you have ample time and the required tools. However, if you are not going to do this work yourself, you can go to a mechanic and get the dent fixed. Mechanics are experts in doing this kind of work and therefore the repair would be so good that you'll hardly be able to find any defect after the task is completed! But all this paintless dent repair Atlanta comes with a price tag! The average cost of dent repair depends upon the size and complexity of the dent. A dent of about 1 - 2 inches is will cost around $100 - $150, whereas, a 3 - 4 inch large dent is repaired at a cost of about $200 or more. However, it should be noted that the above mentioned paintless dent removal cost varies according to the location and also the local labor charges incurred. Also, sometimes the denting is so bad that the whole part needs to be changed, which will then incur costs of different proportions all together. How to Repair a Dent Repairing a dent is not a very difficult procedure. In fact, it one of the easiest 'do it yourself' task, provided you are quite good at external vehicle repairs and also have fair knowledge of the auto parts. This task can be completed in a couple of hours. Here's how to repair a dent. You will http://m.dentdoctor.com/ need dent repair tools such as the drill, spray primer, dent puller, sandpaper, disc for medium surface-conditioning, wooden block, dolly, body filler, 3 - 4 mm drill bit, a hammer, and some vehicle paint. With all these tools in hand, you can now move on to repairing the dent. Determine the mid-point of the dent and then prepare a hole using the drilling machine. Now take the dent puller through the drilled hole and pull the dent puller, in order to straighten the dent. Further, start hammering the frontal side of the dent and simultaneously hold the dolly at its rear side. Now, with the help of the medium surface-conditioning disc on the drill, grate the paint, which is lying at a radius of 1 inch around the dent. Use a body filler to fill up the affected area. Once the body filler dries, sand out the area with the help of a sandpaper and apply about 5 - 6 layers of spray primer on the affected area. Now, once again apply sandpaper to the primer and clear out all the scratches on the dent. Finally, paint the dent with a paint color and material similar to that of the entire vehicle, and you are done. Even a small dent can spoil the overall look of your vehicle! So you need to repair it immediately, either by the procedure to repair the dent yourself, or by giving it to a professional, as now you have an idea of the dent repair cost. Best way is, prevent a dent, drive safely!!! Dent Fixing in Fort Worth solutions are also referred to as paintless dent repair or paintless dent elimination. These strategies focus on obtaining dings and also little dents from the figure of autos. Mobile dent fixing could easily be utilized to heal a large selection of damages. This problems could include door dings, hailstorm damage, minor physique creases, and bumper indentations. It's a great option for those who do not intend to take their auto in to a shop and favor for mobile cars and truck dent repair work professionals in Fort Worth in advance to their estate and repair the little damages that have been inflicted after the auto. Mobile Dent Repair work Mobile dent repair is most often utilized for mild dents as well as damage that establishes as a result of hail storm, a ding to the doorway, or perhaps small bumper imprints. The procedure used helps prep the damaged panel for paint if the paint was spoiled too. Relying on the problems the mobile dent repair strategies could quickly be utilized. It depends on specifically just how adaptable the paint is the quantity of steel that has actually been stretched as well as the overall quantity of damage that has in fact been inflicted. Call today for dent repair service in Fort Worth. Searching for Dent Repair service in Fort Worth Business Dent Repair service in Fort Worth Lots of people ask yourself exactly what type of damages can be fixed making use of mobile dent repair techniques, usually the shallower the dent, the much better the opportunity that it can be cared for. Some think that huge dents are not repairable by this technique; nonetheless likewise those damages that are a number of inches in size can be taken care of. The only requirements is that the dent is superficial and uncreased. This implies that paintlessdentrepairfortworth dents that are really sharp will absolutely not be repairable utilizing the mobile dent repair work procedure. However, it's always possible so it is vital to have actually an incredibly licensed specialist managing dent repair works. Specifically exactly how It Works One of the most typical approaches of repair consists of making use of steel posts as well as body choices that will certainly push the dent out from the under side of the auto panel. In addition, adhesive could quickly be utilized from the outside to draw the dents out. Then counting on the capacity of the expert the fixing can conveniently be gettinged down. This type of repair can be paintlessdentrepairfortworth.info/ taken advantage of on both lightweight aluminum and steel panels. It is crucial that an expert be very qualified or else they could damaged the car additionally more. For instance if a technology owns too tough when producing high areas the pain will fracture and also divide relevance that painting will have to be included. Dent Repair work In Fort Worth Solutions It also relies on the condition the paint joins. Exercise There countless training facilities that provide the education and learning and knowing and knowledge required for professionals to understand mobile dent repair service. The paintless dent repair work course will certainly show the capabilities essential consisting of pushing, adhesive as well as pull procedures, and also will certainly additionally instruct how to supply an appropriate estimate. When a specialist surfaces their training program they are really prompted to exercise the new treatments they have really found out. Some courses recommend daily as this will certainly keep the know-how at the center of their repair work technique and will absolutely permit them to understand the ability. Dents can easily be unattractive on any type of sort of car, nevertheless taking it right into a store can be an ache as well as could conveniently cost quite a bit of cash money. That's why it's a great idea to check out dent repair mobile remedies in Fort Worth The dent can be eliminated swiftly and effortlessly and the technician will certainly entail you. By locating a well qualified mobile dent eliminators in Fort Worth an auto can look its excellent despite the age or the damages brought upon. Locate us here - http://paintlessdentrepairfortworth.info/ Fixing a dent in a garage door is feasible in case you have been doubting. What they do would be to place the dent within the garage door to the ideal angle that will make it easy for the whole process to be conducted efficiently. Not a lot, of thinking went into putting the dent there. Other times it may not be you that causes a dent in your garage door. This is because many kids have no clue about the use of the garage door. Nicely, some might be, but we will be talking about metal or aluminum, garage doors.
Size does matter in a dented door, based on the size of the dent within the garage door. If the dent is about the size of just one of your panel on your garage door, it's greatest to fix or replace the whole panel, so the size of the dent doesn't matter. At times the little holes are fixed in a way that differs from the large ones. Smaller dents could be worked out in many various methods to bring the dent out. In the event you happen to have a mallet larger than the dent, opt for the rubber kind. The rubber mallet works just like the hammer hence you need to utilize its rubber material to the maximum. Utilizing the Paintless Dent Repair Fort Worth mallet like a hammer, you hit the dented inside towards the outside. This technique can be utilized on bigger dents, then a mallet size, but you need to do it with great care. An additional method along with a fairly clever one are to use your plunger. You are able to place the plunger on leading of the dent paintlessdentrepairfortworth.info/ if the latter is too small. You'll need to http://www.nodent.net/ go through the inside component of the dent in case it's larger than the plunger. Now attempt to pull outward. The dent may also be removed by pulling it out. In the event you tend to make use of a big dent on your garage door then all will probably be nicely. All you need to do is make use of the methods given above to make that large dent turn into a little desirable size. What you should do in order to get that dent smaller is by putting something in it to achieve what you would like. Its greatest in the event you head to the store and discover how you are able to fill out that dent. You'll need to opt for the ideal store which will provide you with the very best fill out for your dent. Make certain you put in mind what the manual guide tells you to ensure that you get a clear picture of how you are able to fill the dent. If require be, use all of the given points to fill the dent within the garage door. Once in a whilst you'll have to push the dent from the other side of the door. You don't need to give up with regards to fixing your dent in the garage door simply because its feasible. LAS VEGAS--(BUSINESS WIRE)--At the Kitchen & Bath Industry Show (KBIS) this year, Wilsonart, a leading provider of total engineered surfacing solutions, unveils five major product category introductions. The introductions include the brand new Wilsonart® HD® Laminate with Antimicrobial Protection and AEON(TM) Scratch & Scuff Resistance; four new additions to the Wilsonart® Residential Laminate Collection; four new additions to the premier Wilsonart® Quartz Collection; seven boomerang Retro Renovation® by Wilsonart, part of Wilsonart's Virtual Design Library (VDL) "Retro" category; and 19 new additions to the Wilsonart® Solid Surface Collection. Wilsonart® HD® Laminate with Antimicrobial Protection Wilsonart is continually improving upon its laminate products to provide the most innovative surfacing solutions. Wilsonart® HD® Laminate now combines the most dramatic designs and textures with Antimicrobial Protection and Enhanced Scratch and Scuff-Resistant AEON(TM) Technology to produce the best laminate for countertops and work surfaces. All Wilsonart HD Laminate designs will include this enhancement. Wilsonart's enhanced antimicrobial protection is built directly into the laminate to protect the surface against damaging microbes such as mold, mildew, and bacteria that cause odors. Visit www.wilsonart.com/laminate/wilsonart-hd for samples. Wilsonart® Residential Laminate Four new designs from the Wilsonart® Residential Laminate Collection closely resemble the natural look and sophistication of stone, without sacrificing the durability and sustainability of laminate. Visit www.wilsonart.com/laminate for samples this spring. Wilsonart® HD® Laminate Collection Cipollino Bianco | Mirage Finish Antimicrobial Protection and AEON(TM) Scratch & Scuff Resistance, a dramatic large-scale marble look suggestive of quartz with unique veining and crystal structures in warm neutral tones and deep accents. Cipollino Grigio | Mirage Finish Antimicrobial Protection and AEON(TM) Scratch & Scuff Resistance, a marble reminiscent of a large-scale quartz with striking movement and unique crystal veining in a warm slate grey. Wilsonart® Premium Laminate Collection Leche Vesta |Textured Gloss Finish with AEON(TM), a medium scale abstract resembling packed stone with a white background plus grey and black medium size particulates. Mercury Vesta |Textured Gloss Finish with AEON(TM), a medium scale abstract resembling packed stone with a cool grey background plus grey, taupe and black medium size particulates. Wilsonart® Quartz The Quartz Collection celebrates discovery with designs inspired by locations and cultures around the world. The newest introductions range from large-scale veining and movement for a dramatic design, to fine, subtle patterns perfect for a sleek and modern update. Visit www.wilsonart.com/quartz for samples this spring. Anatolia (Q4021), a distinctive tea rose marble quartz countertop design with large mother of pearl features, pink veining and subtle white highlights. King's Crown (Q4018), a striking quartz countertop design with a balanced blend of cream and mushroom, subtle smoky black veining and hints of garnet. Isselburg (Q4013), a natural style quartz countertop design in a flowing crystalline structure of light taupe and pale white. Grey Lake (Q1009), a dark grey solid quartz countertop design. Retro Renovation® by Wilsonart Virtual Design Library Laminate Seven nostalgia-driven boomerang patterns designed in collaboration with Retro Renovation's Pam Kueber and Kate Battle make their debut, joining the Wilsonart® Virtual Design Library (VDL) "Retro" category. From "First Lady Pink" to "Rock 'n' Roll Ruby," the colors are designed to appeal to the growing number of homeowners restoring and decorating their kitchens Bathroom Renovations Sydney Pro and bathroom in midcentury and vintage style. Visit www.wilsonart.com/vdl for samples February 1. Wilsonart® Solid Surface For a more neutral style, the 19 new Solid Surface designs range from small to large particulates and include varieties of veining and movement. The Collection combines an assortment of neutrals that have grown in popularity in today's interiors, allowing for a bold mix of materials and pops of color. Grey continues to be a popular color choice, offering a wide range of hue and saturation, while natural shades of white and beige offer a lighter, brighter touch. Visit www.wilsonart.com/solid-surfaces for samples this spring. Wilsonart at KBIS Come by booth N727 at KBIS to explore these new Wilsonart surfacing solutions. Also at the http://www.devel.com.au/bathroom-renovations-sydney/ Wilsonart booth will be industry voices Danny Seo, green lifestyle expert and editor-in-chief of Naturally, Danny Seo Magazine; Pam Kueber, publisher of Retro Renovation; Grace Jeffers, design historian and materials expert; and Dr. Charles Gerba aka "Dr. Germ," microbiologist, Professor at the University of Arizona and expert on antimicrobial surfaces. To make an appointment with a Wilsonart representative or any of these experts, email [email protected]. For more information, visit www.wilsonart.com or call 800-433-3222. About Wilsonart Wilsonart is one of the world's leading manufacturers and distributors of High Pressure Laminates, Quartz, Solid Surface and other engineered surfaces used in furniture, office and retail space, countertops, worktops and other applications. The company operates under the Wilsonart®, Resopal®, Polyrey®, Ralph Wilson®, Arborite® and Durcon® brands and has achieved success through a combination of outstanding service, high-quality products and a focus on continuously redefining decorative surfaces through improved performance and aesthetics. For more information, visit Wilsonart.com or connect with us on Instagram, and Twitter. When "The Godfather: The Coppola Restoration" was released on DVD and Blu-ray at the end of September, many people saw the classic films in a different light. One of those people was director Francis Ford Coppola. Assistance from new technology (and a certain Mr. Steven Spielberg) has the films looking truer to the director's vision then they did in theaters 30 years ago.
At the time of the first film's release (1972), the practices of preserving and copying film negatives were not as streamlined as they are today. As a result, the original negative of "The Godfather" was destroyed when the film struck box-office gold and Paramount used it to print copy after copy (the film would earn over $134 million in theaters throughout its run). It took until the late 1990s for the people at Paramount to realize the legacy of two of their prize pictures (almost universally considered two of the best films ever made) might be in trouble. Problem was, the technology to clean up the film prints properly just wasn't far enough along https://www.allstate.com/tools-and-resources/home-insurance/water-damage.aspx for the massive overhaul "The Godfather" required. At that point, the company placed all "The Godfather" film elements it had left in a cold vault to preserve them until the technology "caught up" - roughly the equivalent of Walt Disney freezing his head. Then, in 2005, DreamWorks pictures, the brainchild of Speilberg, Jeffrey Katzenberg and David Geffen, was acquired by Viacom, the parent company of Paramount. On a whim, Coppola wrote to Speilberg asking him to help push forward the restoration of "The Godfather" films. Spielberg being Spielberg, he quickly got the ball rolling. But, even with advanced technology, the restoration of the first two parts of "The Godfather" was no easy task (part three wasn't ignored because it is a lesser picture - which it is - the film negatives were just in far better condition). No single usable negative of "The Godfather" remained that was suitable as a source. So, the company tasked with restoring the film, The Film Preserve (which also completed restorations of classic films like "Lawrence of Arabia", "Rear Window", and "Spartacus" ), gathered a bunch of backup film materials and an Italian-subtitled print to use as a color reference. The Film Preserve then worked with Coppola, Gordon Willis (the cinematographer on the original films), and Allen Daviau, a cinematographer on movies like "E.T." who is considered a leading historian of photographic technology, to get expert opinions. The entire process of restoring the film, from Spielberg to DVD release, would take over two years. While most film restorations are done by applying a photochemical to negatives, since that was impossible with "The Godfather" films, the process had to be done via digital technology. Film Preserve technicians carefully scanned the film materials into digital form 4K files (video made up of 4,000 lines of horizontal resolution, or four times the quality of HDTV), and cleaned up dust specks, lines and other flaws frame by frame. Ultimately, more than 1,000 man hours were spent removing digital dirt and scratches from the two films. It was also during the restoration process that technicians noticed some imperfections that had been in the films since their theatrical release, which somehow managed to fly under the radar. For example, the classic scene in "The Godfather" when Michael Corleone commits his first acts of murder in an Italian restaurant had originally been incorrectly processed. The scene was filmed on two separate nights, so the footage was processed separately, and the picture quality of many of the shots did not match up. Through the magic of digital technology, this error was corrected for the new DVD release. When placed side-by-side with the 2001 DVD release of the films, the new presentations offer a very different picture - at least for film aficionados. Blacks are darker, colors more vibrant, the trademark fade-away transitions much smoother, and, perhaps most notably, the films are now basked in a golden glow that better Fort Lauderdale Restoration Pros FL suits the epic and tragic story. While many classic films have been lost forever due to film stock damage, it is a testament to digital technology that great, great films like "The Godfather" and "The Godfather: Part II" now look better than they did projected on film screens three decades ago. By: Shad Connelly Article Directory: http://www.articledashboard.com news.inventhelp.com The U.S. State Department is producing anti-Islamic State propaganda to persuade American and other would-be jihadis not to join the extremist group. It's ham-handed, and often sarcastic, and unlikely to have the intended effect. Why? Because the department fails to understand how Islamic State attracts recruits in the first place. One way to make sense of all this -- bear with me here -- is to look at the appeal of Alcoholics Anonymous. AA does not recruit members, it attracts them. Long experience suggests that people who impulsively make decisions that actually require a long-term commitment will almost certainly fail. As the entry point for joining, AA thus asks prospective members to first make a commitment to not drink. Ads for the organization never try to seduce alcoholics into joining. The focus instead is on what AA can do for them. If they want what it offers - sobriety -- and are committed to working toward it, AA says, then join. And so with Islamic State. Islamic State propaganda pulls no punches. Beheading videos, boasts about enslaving women, promises of austere Sharia-led lives, it's all there. You want what it offers? Come along, because Islamic State wants people who make a positive commitment to join. The group's presentation is professional and serious, particularly through its Al Hayat Media Center (no connection to the unaffiliated Egyptian TV channel with a similar name), and aimed specifically at non-Arabic speakers via videos and a magazine based on al Qaeda's infamous Inspire. The strategy seems to be working, though number vary. From 12 to 300 Americans have left the country to join Islamic State. Recruitment in Europe and the Arab world is reportedly strong. Some even claim Islamic State are drawing foreign recruits away from the Taliban. The State Department's propaganda uses a negative message to counter the attraction of Islamic State media. Started in 2011, it was only in foreign languages, moving into social media -- and English - in 2013. This year the work started showing up on YouTube. The current theme of State's efforts is "Think Again, Turn Away" and the messaging can be found on YouTube, Facebook, Twitter, Tumblr and even on the sides of buses in New York City. One YouTube video includes subtitles such as "learn useful skills, such as blowing up mosques" and "crucifying Muslims." Another features oil being poured on the ground framed as "squandering public resources." The content is seemingly written more to appeal to Washington than potential jihadis, as you can see in this example. A lot of the messaging mocks potential recruits, claiming, for example, they read "Islam for Dummies" before heading to Syria. Under Secretary of State for Public Diplomacy and Public Affairs Richard Stengel said, "We have evidence that there are young people who are not joining [Islamic State] because we have somehow interceded. They're reading the messages, they're hearing the messages." State's own description of its work in social media is "contesting the space," but it has not provided evidence that its messaging has dissuaded anyone from joining Islamic State. What details are made public focus on numbers of "likes" and views. The cost of all this runs between $5 million and $6.8 million a year. Oddly, State's and Islamic State's messaging are not all that different, at least in the topics covered. Both stress that recruits are unlikely to survive fighting. State paints that as a terrible choice, while Islamic State categorizes it as a positive one leading to martyrdom. Both feature photos of Christian churches Islamic State destroyed, with obviously different judgments of the act. Both talk about Western life, with Islamic State emphasizing its spiritual emptiness. Both sides agree that Muslims are killing Muslims. But the view expressed in State's messaging is that all Muslims are the same, while Islamic State says some (pretenders to the faith who abandoned Sharia) are not pious and it is thus not a violation of the Koranic injunction against internecine violence to kill them. A core audience agrees; one report says 92 percent of Saudi Sunnis see Islamic State' activities as religiously legal. The United States' anti-Islamic State messaging reminds one of the anti-drug "Just Say No" campaign led by Nancy Reagan in the 1980s, which quickly morphed into comic fodder. On the other hand, as with AA, offering people a positive message -- you can have what we have -- seems more effective. To an alienated young person already looking askance at his society, what Islamic State says may seem more attractive than the mocking, negative message of the State Department. Sadly, many Islamic State recruits are committed to giving their lives for jihad, and its propaganda message reinforces that well. The marketing is slick, but more than that, the message resonates with its intended recipients. State's messaging says you're going to hell. Islamic State says you're headed to heaven. Both are literally propaganda to die for. Who is winning in that match-up? Demonstrators hold placards outside the U.S. embassy, near where a 9/11 anniversary memorial was being held, in central London September 11, 2011. The memorial was to commemorate the September 11, 2001 attacks in the U.S.. REUTERS/Paul Hackett We look to regional, national and international interior design blogs and other media -- such as Florida magazines, newspapers, books and websites -- for the latest in trends on home decorating and design. In addition to providing information on what's new in the design world, they can inspire you to take action in your own home, provide resources for learning more about design fundamentals and help you get inspired for a future home improvement project. You can find more media & bloggers in St Johns, Saint Johns, Jacksonville, St. Johns and Miami. More
The first Boca Raton Restoration Experts Service Area few things http://ablenationalrestoration.com/ that come to our mind when we think of Florida are theme parks, South Beach, and luxurious high-end hotels. However, there is much more to the state. If you stay away from Orlando and Miami, things get a lot more affordable. A great option to explore Florida on a budget is the equivalent of exploring the Palm Beach County. It offers luxury, history, natural respite, and so much unadulterated fun that you'll be exhausted but not theme-park broke.
Palm Beach County is the largest county in the state, home to old Boca Raton Restoration Experts Service Area money, a Boca Raton Restoration Experts Service Area rich history, and a burgeoning biotechnology industry. The county not only includes famous luxury towns, like Palm Beach and Boca Raton, but http://royal-cleaners.com/ also the metropolitan West Palm Beach, rural Loxahatchee, charming Delray Beach, and laid-back Jupiter. INTRODUCTION
Indoor air quality researchers typically focus their attention on biological, chemical and particulate contamination of indoor environments and the health effects and discomfort that these contaminants may cause. Indoor environmental investigations typically rely on short-term sampling techniques that provide only a snapshot of contaminant concentrations in the indoor environment at the time of sampling. HVAC filter dust is a potential resource that has received less attention and may enhance our understanding of indoor occupant exposure. Filters are typically in place for extended periods of time and have the potential to serve as long-term samplers of the indoor environment. Furthermore, HVAC filter dust can be collected with minimal effort and analyzed for a broad range of contaminants. This paper focuses on bacteria, fungi, and heavy metals captured on HVAC filters and investigates how these parameters vary with filter and building characteristics. Several studies have measured the concentration of bacteria and fungi in indoor environments, especially in air and settled dust (e.g., Bouillard et al., 2005; Dales et al., 1997; Verhoeff and Burge, 1997). However, the reported concentrations are difficult to compare because they vary considerably depending on sampling technique and sampling location, among other factors. An alternative approach for investigating air and settled dust would be to analyze the dust that collects on HVAC filters. A recent study has suggested that HVAC dust may provide an integrated measure of airborne contamination levels in an indoor environment (Tringe et al., 2008). HVAC filters are able to retain biological particles and microorganisms can survive, accumulate, and, under certain conditions, multiply on HVAC filters (Farnsworth et al., 2006; Foarde and Hanley, 2001; Kemp et al., 1995; Kemp et al., 2001; Moritz et al., 2001; Simmons and Crow, 1995). In addition, a number of studies suggest a relationship between Sick Building Syndrome (SBS) symptoms and the presence of microorganisms on filters (e.g., Schleibinger and Ruden, 1999). Several researchers have also studied heavy metal concentrations in house dust and the correlation with potential indoor and outdoor sources and particle size distributions (Al-Rajhi et al., 1996; Chattopadhyay et al., 2003; Decker et al., 2002; Kim et al., 1998; Tong, 1998). Despite these efforts, we are not aware of any research that utilizes HVAC filters as samplers to characterize metal concentration levels indoors or that examined the influence of HVAC systems and potential sources on metal concentrations found on the HVAC dust. While both microbial populations and metals found indoors have been studied, the relationship between their presence in HVAC filter dust and critical characteristics of both the particular HVAC system and the building remains unclear. This research compares the contaminant levels found in HVAC filters with different filter efficiencies and provides insight into potential sources of contamination. This investigation is part of a broader evaluation of the utility of using filters as samplers for the indoor environment. METHODOLOGY Eight residential and one commercial building in Austin, Texas were selected for this investigation. These sites represent a sample of convenience and not a random sample. To characterize the sites considered, data was collected regarding the year the buildings were built, number of occupants, past or current presence of smokers, proximity to major highways, presence of attached garage, filter location, and conditioned volume. Two sets of HVAC filters were collected from each site, approximately three months apart. All filters were stored in a 4[degrees] C (39 [degrees]F) environmental chamber maintained at a relative humidity (RH) of approximately 70% until the analyses were performed within a few weeks following collection. Characterization of Sites and Filters The filters were categorized according to the minimum efficiency reporting value (MERV) as determined by ASHRAE Standard 52.2 (ASHRAE, 2007) and reported by the manufacturers. The sample included seven low-efficiency filters (MERV <5), seven mid-efficiency filters (MERV 5-8) and four high-efficiency filters (MERV 9-14). Filter pressure drop measurements were performed at filter installation and removal using an Energy Conservatory DG700 digital manometer, and the mean value of these two measurements characterized the mean filter pressure drop. Mean flow rates across each filter in fan-only mode were measured using an Energy Conservatory True Flow Plate. By monitoring the HVAC systems two or three times during the cooling season for 24 hours approximately every month, we measured the cooling duty cycle, which is an estimate of the fraction of time that the HVAC system is running during the cooling season. In addition, during the monitoring events, the temperature and RH in the HVAC system return plenum were also recorded. To estimate the mass accumulated on each filter, we subtracted the mean weight of three unused filters from the weight of the used filter using a balance (Sartorius B310S). Table 1 summarizes the instruments used during the investigation. Table 1. Summary of Instrumentation Measurement Manufacturer Model Accuracy Temperature Onset Hobo U10 [+ or -]0.4[degrees]C (0.7[degrees]F) Relative humidity Onset Hobo U10 [+ or -]3.5% Pressure drop Energy DG 700 [+ or -]1% or Conservatory 0.2 Pa (0.0008 IWC) Air flow Energy True Flow Plate [+ or -]7% Conservatory Weight Sartorius Balance B310S [+ or -]0.001 g Microbial and Metal Analyses Two samples of dust from each filter were acquired by shaking and scraping the dust material off the filters. The samples were subsequently analyzed for microbial and heavy metal concentrations. The enumeration of culturable bacteria and fungi was completed using the standard spread plate method 9215C (APHA, 1998). The microorganisms present in the HVAC filter dust were transferred into a phosphate buffer solution (PBS, 8 g/L NaCl, 0.2 g/L KCl, 1.44 g/L [Na.sub.2][HPO.sub.4], and 0.24 g/L [KH.sub.2][PO.sub.4]) by sonication and vortexing for 10 minutes each. For bacterial enumeration, a 0.1 ml aliquot of PBS was plated on [R.sub.2]A agar plates containing 0.04% cycloheximide. For fungal determinations, a 0.1 ml aliquot of PBS was plated on Sabouraud Dextrose Agar (SDA) plates containing 0.01% chloramphenicol. Bacterial plates were incubated for 3-7 days at 30 [degrees]C (86 [degrees]F), while fungal plates were incubated for 7-14 days at room temperature (approximately 23 [degrees]C/73 [degrees]F). After incubation, the number of bacterial and fungal colonies formed was counted and the results were used to estimate the microbial concentration in the dust, expressed as colony forming unit (CFU) [g.sup.-1] dust. The analysis was performed three times for each dilution and the average number of colonies formed was recorded. The ability of the microorganisms to form spores was also tested by pasteurizing an aliquot of the samples for 15 minutes at 75[degrees] C (167 [degrees]F) and then plating the samples as described above. Any colonies that formed were assumed to have originated from spores and to represent the spore-forming fraction of the population. Heavy metal concentrations in the HVAC filter dust were determined by atomic absorption spectroscopy (Perkin Elmer AAnalyst 600). Dust samples were digested via the microwave-assisted digestion method 3030K (APHA, 1998). This method consists of a nitric acid digestion under controlled pressure and temperature conditions that facilitate the transfer of the metals present in the particles into the liquid extract. The liquid extract from each sample was analyzed for selected heavy metals (Pb, As, Cd) according to method 3111B (APHA, 1998). To ensure the accuracy of the measurements, reagent blanks and periodic calibration checks were also analyzed. A nonparametric statistical method, the Wilcoxon Rank-Sum Test, which does not assume any specific distribution of the data, was applied to compare and identify dissimilarities between the different data groups. When comparing the different data groups, a significance level of 0.1 was assumed owing to the small sample size and the conservative nature of this statistical test. RESULTS AND DISCUSSION Table 2 characterizes the nine sites and the presence of likely sources of contamination. Site 9 was the one light commercial building included in the study. All the sites were relatively close to major highways and five sites had attached garages. Sites 2, 3, 4, and 9 were attached to other dwellings. Four sites had the filter located at the unit, while five were located at the return register. In Sites 3 and 9, multiple filters were present. Cooling duty cycles of the sites ranged from 9 to 34%. There were no smokers occupying any of the sites, although Site 2 had smokers in the past. Sites 3 and 4 were located in the same residence with two separate and independent HVAC systems for different floors of the residence. The sites summarized in Table 2 represent a range of HVAC systems and operating characteristics for this region of the country. Table 2. Site Characteristics Site # Year Number of Proximity Attached Carpet Filter Built Occupants to Garage Location Highway, km (miles) 1 1975 2 1.0 (0.62) Yes No Unit 2 1973 2 0.6 (0.37) Yes Yes Unit 3 1998 1 0.2 (0.12) Yes No Register (2) 4 1998 1 0.2 (0.12) Yes Yes Register 5 1949 2 1.8 (1.12) No No Register 6 1941 4 1.1 (0.68) No Yes Register 7 Late 4 0.6 (0.37) No Yes Unit 70s (1) 8 1984 3 0.5 (0.31) Yes Yes Unit 9 1995 3 0.2 (0.12) No Yes Register (3) Site # Year Conditioned Cooling Built Volume, Duty [m.sup.3] Cycle, ([ft.sup.3]) % 1 1975 422 (14,900) 14 2 1973 309 (10,900) 16 3 1998 114 (4,020) 9 4 1998 227 (8,010) 27 5 1949 276 (9,740) 32 6 1941 324 (11,400) 29 7 Late 259 (9,140) 34 70s (1) 8 1984 308 (10,900) 15 9 1995 656 (23,200) 19 (1) Estimated based on neighborhood and nearby homes. (2) Three filters in different return grilles were present at this site. (3) Two filters in different return grilles were present at this site. Table 3 summarizes the characteristics of the 18 HVAC filters, two from each site, that were evaluated during the project. The mean pressure drop across the filter, [DELTA]P, and the mean volumetric airflow through the HVAC system, Q, were obtained by averaging the values obtained at installation and at removal. For a few filters, we were not able to measure the filter pressure and supply plenum pressure (required for the flow measurement) at filter installation, so the measurements collected at the time of filter removal are reported. For Filter 2 of Site 2, the value reported represents the observation acquired at installation. The mean temperature and RH observed at the HVAC return plenum during the monitoring events are also reported. These values do not represents mean levels during the period the filters were in place, but only what was observed during the monitoring visits. Table 3. Filter Characteristics Site Filter Filter Pressure Drop Air flow Q, Efficiency [DELTA]P, Pa (IWC) [m.sup.3]/h (cfm) 1 1 Low 22[+ or -]0.2 1710[+ or -]120 (0.088[+ or -]0.0008) (1010[+ or -]71) 2 Mid 50[+ or -]0.5 1670[+ or -]120 (0.20[+ or -]0.002) (981[+ or -]69) 2 1 Low 1280[+ or -]90 (754[+ or -]53) 2 Low 58[+ or -]0.6 1780[+ or -]130 (0.23[+ or -]0.002) (1050[+ or -]74) (1) 3 1 High 37[+ or -]0.4 1420[+ or -]100 (0.15[+ or -]0.002) (837[+ or -]59) 2 Mid 33[+ or -]0.3 1450[+ or -]100 (0.13[+ or -]0.001) (851[+ or -]59) 4 1 Low 64[+ or -]0.6 941[+ or -]66 (0.26[+ or -]0.002) (554[+ or -]39) (2) (2) 2 High 54[+ or -]0.5 1000[+ or -]70 (0.22[+ or -]0.002) (589[+ or -]41) 5 1 Mid 78[+ or -]0.8 1990[+ or -]140 (0.31[+ or -]0.003) (1170[+ or -]82) (2) 2 Low 59[+ or -]0.6 1940[+ or -]140 (0.24[+ or -]0.002) (1140[+ or -]80) 6 1 High 89[+ or -]0.9 1800[+ or -]130 (0.36[+ or -]0.004) (1060[+ or -]74) (2) (2) 2 Mid 92[+ or -]0.9 1660[+ or -]120 (0.37[+ or -]0.004) (975[+ or -]68) 7 1 Low 49[+ or -]0.5 1300[+ or -]91 (0.20[+ or -]0.002) (763[+ or -]54) 2 Mid 81[+ or -]0.8 1140[+ or -]79 (0.32[+ or -]0.003) (669[+ or -]46) 8 1 Mid 48[+ or -]0.5 1150[+ or -]80 (0.19[+ or -]0.002) (676[+ or -]47) (2) (2) 2 Low 27[+ or -]0.3 1200[+ or -]84 (0.11[+ or -]0.001) (705[+ or -]49) 9 1 High 76[+ or -]0.8 2730[+ or -]190 (0.30[+ or -]0.003) (1610[+ or -]110) (2) 2 Mid 81[+ or -]0.8 2790[+ or -]200 (0.32[+ or -]0.003) (1640[+ or -]120) Site Filter Filter Temperature, RH, % Days Mass on Efficiency [degrees]C in Filter, g ([degrees]F) Service 1 1 Low 24.7[+ or -]0.50 70.8 88 (76.5[+ or -]33) [+ or -] 4.1 2 Mid 95 2 1 Low 2 Low 26.6[+ or -]0.83 66.7 95 4.5 (79.8[+ or -]34) [+ or -] [+ or -] 3.7 0.002 3 1 High 25.5[+ or -]0.77 62.4 85 (78.0[+ or -]33) [+ or -] 4.5 2 Mid 99 1.3 [+ or -] 0.002 4 1 Low 0.3 [+ or -] 0.002 2 High 26.1[+ or -]0.87 58.4 85 (78.9[+ or -]34) [+ or -] 3.5 5 1 Mid 2 Low 24.4[+ or -]1.9 63.0 87 0.3 (75.9[+ or -]35) [+ or -] [+ or -] 5.9 0.002 6 1 High 2 Mid 24.8[+ or -]1.3 58.9 90 4.2 (76.6[+ or -]34) [+ or -] [+ or -] 5.0 0.002 7 1 Low 26.0[+ or -]0.30 60.1 87 (78.8[+ or -]33) [+ or -] 2.9 2 Mid 92 4.1 [+ or -] 0.002 8 1 Mid 2 Low 24.7[+ or -]1.3 52.5 88 (76.5[+ or -]34) [+ or -] 3.9 9 1 High 2 Mid 24.0[+ or -]1.6 54.2 82 6.5 (75.2[+ or -]35) [+ or -] [+ or -] 5.3 0.002 (1) Only initial measurement (2) Only final measurement For some filters, the days in service was not known, because it was the filter the homeowner had in place when we started the investigation. For seven filters it was possible to estimate the mass accumulated over the service life because these filters were weighed before use. As expected, we observed a correlation between filter efficiency and particle mass accumulated on the filter. The mean mass accumulated on the low-efficiency and mid-efficiency filters was 1.7 and 4.0 g, respectively. There may also be a correlation between the mass of particles accumulated on filters and the presence of carpet in the house. The mean mass accumulated on the filters from the sites with and without carpet was 3.9 and 0.8 g, respectively. Carpets tend to accumulate more dust than bare floors because they are harder to clean than other types of floor. As a consequence, particle resuspension from carpet is expected to be greater than from other floor surfaces (Yoon and Brimblecombe, 2000). As demonstrated by Corsi et al. (2008), resuspension of [PM.sub.10] is much larger than [PM.sub.2.5] suggesting that even the low MERV filters can retain many of the larger particles from vacuuming activities. Figure 1 presents the mean culturable microbial concentrations in the HVAC filter dust from the nine sites investigated, expressed as CFU/g dust. Since two filters were collected and analyzed from each site, 18 total samples are represented in Figure 1 and the mean value for each site is shown. For each site, the left bar indicates the culturable concentration of bacteria while the right bar represents the culturable fungal concentration. The height of each bar indicates the mean culturable concentration and originated from the counts of the microbes with the ability to form colonies on the specific agar plates described air conditioning repair sydney in the Methodology section. The bottom section of each bar represents the spore forming fraction of the population, which is the fraction of the viable microbial concentration able to survive the pasteurization treatment. Only the error bars for the total height of the columns are shown in the figure and the bars on the lower portions were of similar magnitude. [FIGURE 1 OMITTED] The culturable bacterial concentrations were consistently greater than the fungal concentrations for the nine sites investigated. The bacterial concentrations ranged from [10.sup.5] to [10.sup.7] CFU/g while the bacterial spore concentrations were typically two orders of magnitude lower, ranging from [10.sup.3] to [10.sup.5] CFU/g. The mean concentration across the sites was 1.4x[10.sup.7] CFU/g for bacteria and 1.2x[10.sup.5] CFU/g for bacteria spores. Culturable fungal concentrations were consistently lower than bacteria levels and varied in the [10.sup.4] -[10.sup.6] CFU/g range. Fungal spore concentrations were typically the lowest of all four categories and varied in the [10.sup.2] - [10.sup.3] CFU/g range. The mean concentration across the sites for fungi and fungal spores was 1.1x[10.sup.6] and 1.4x[10.sup.3] CFU/g, respectively. To put these microbial concentrations in context, these values are similar to those observed in soil for both bacteria and fungi (Lovell et al., 1995; Toro et al., 1997). The culturable bacterial and fungal concentrations observed in the current study are slightly higher than the values reported in the literature for settled dust (Bouillard et al., 2005; Chew et al., 2003). This difference may be attributable to the HVAC airflows that deliver airborne microbes and nutrients to HVAC filters. Many studies have suggested that microbial contamination of HVAC filters occurs because filters collect sufficient organic material and nutrients to support microbial growth (Burge, 1987; Kemp et al., 2001; Pejtersen, 1996). Kemp et al. (1995) also observed enhanced fungal growth when additional nutrients were delivered to HVAC filters. The culturable microbial concentrations encountered in this study suggest that HVAC filters in residential buildings in a humid environment like central Texas during the cooling season represent a hospitable environment for microbial proliferation. The microbial concentrations measured in this study represent only the culturable fraction of the microbial population able to grow on the specific media utilized. Toivola et al. (2002) estimated that only 1% of the microbial population indoors is culturable and molecular based tools offer the promise of being able to detect a much greater fraction of the microbial community, not just the culturable fraction. However, the extraction of DNA directly from HVAC filter dust cake is particularly challenging and, as reported by Ramakrishnan et al. (2006), the use of standard commercial DNA extraction kits often generates inconsistent results. Nevertheless, the authors are currently investigating these techniques and their applicability to further characterize microbial populations on HVAC filters. Table 4 summarizes the median microbial concentrations observed on filters with different MERV ratings. Median microbial concentrations on HVAC filters were relatively consistent across filters with different removal efficiencies. The median concentrations were typically within one order of magnitude of each other and application of the Wilcoxon Rank-Sum Test to the data did not find any significant differences between filters with different MERV ratings. Despite this general similarity, high-efficiency filters had the lowest median microbial concentrations for bacteria, fungi and fungal spores. As reported by Waring and Siegel (2008), the particle mass that accumulates on HVAC filters strongly depends on their removal efficiency, and high-efficiency filters capture a greater mass of particles. Typical bacteria and fungi cell sizes vary from less than a micron to several microns, depending on the microbial species. Therefore, high-efficiency filters are more likely to retain an elevated number of microbial cells. A high-efficiency filter also captures more non-biological particles, potentially providing microorganisms with a greater amount of substrate and nutrients, and therefore promoting their growth. However, the presence of non-biological particles will also increase the mass captured on the filters and serve to diminish the measured microbial concentration because it is based on CFU per unit mass (both biotic and abiotic) of dust captured. This is one possible explanation for the decreased microbial concentrations observed on the dust captured in the high-efficiency filters. Table 4. Median Microbial Concentrations in HVAC Filter Dust for Filters with Different Efficiencies Bacteria Bacterial Spores Fungi Fungal Spores Filter MERV CFU/g Low 6x[10.sup.6] 5x[10.sup.4] 4x[10.sup.5] 1x[10.sup.3] [+ or -] [+ or -] [+ or -] [+ or -] 6x[10.sup.5] 9x[10.sup.3] 7x[10.sup.4] 1x[10.sup.3] Mid 9x[10.sup.5] 7x[10.sup.4] 6x[10.sup.5] 8x[10.sup.2] [+ or -] [+ or -] [+ or -] [+ or -] 2x[10.sup.5] 7x[10.sup.3] 1x[10.sup.4] 1x[10.sup.3] High 3x[10.sup.5] 7x[10.sup.4] 1x[10.sup.5] 6x[10.sup.2] [+ or -] [+ or -] [+ or -] [+ or -] 6x[10.sup.4] 3x[10.sup.3] 9x[10.sup.4] 7x[10.sup.2] Figure 2 http://www.homeairconditionerssydney.com.au/ summarizes the mean HVAC filter dust concentrations of lead, cadmium and arsenic for each site. Pb had consistently the greatest concentration in all the samples with values ranging from 5.4 to 28.6 [micro]g/g dust. The median Pb concentration across all samples was 13.0 [micro]g/g. HVAC filter dust concentrations for Cd and As were lower than Pb concentrations with values varying in the 0.5 - 6 and 0.8 - 7.3 [micro]g/g ranges, respectively. The median concentrations of Cd and As across all the samples analyzed were 1.9 [micro]g/g and 1.4 [micro]g/g, respectively. The metal concentrations reported in the literature for indoor dust are similar to those reported here for HVAC filter dust and are typically in the [micro]g/g range, with Pb and Zn concentrations that tend to be higher than the other metals and can reach the mg/g range (Al-Rajhi et al., 1996; Lisiewicz et al., 2000; Turner et al., 2006). [FIGURE 2 OMITTED] Sites 5, 6 and 7 had higher Pb concentrations than the rest of the sample. None of the three sites had attached garages or is located adjacent to a major highway, suggesting that leaded gasoline is not the major source of indoor lead. Sites 5 and 6 were the oldest sites investigated and we hypothesize that the elevated Pb concentration was derived from leaded paint, still in use when the residences were built. Several researchers (Chattopadhyay et al., 2003; Kim et al., 1998; Tong, 1998) provide evidence for this hypothesis. There was uncertainty about the age of Site 7, the other site with an elevated Pb concentration although it was located in a neighborhood constructed in the 1970s and was likely to have contained leaded paint. Site 3, the newest residence investigated had the lowest Pb concentration again supporting the hypothesis that leaded paint is an important contributor to indoor lead levels. A correlation between the age of a property and Pb levels in settled dust has also been observed by other researchers (Adgate et al., 1998; Kim et al., 1998; Tong, 1998). However this correlation is not entirely consistent throughout our study; for instance, Site 4, which is also a new residence, had a higher Pb concentration than several older sites in the study so other factors may be important. At a given site, our data suggests that a correlation between the Pb, Cd and As metal concentrations may exist, as suggested by Sites 5, 6, and 7. In these sites, the concentrations of the three metals analyzed are all above the median values observed in this study suggesting a common source, or coincident sources, of metal contamination. Table 5 summarizes the median concentrations of Pb, Cd and As in HVAC filter dust collected on filters with different removal efficiencies. The median metal concentrations for the high-efficiency and low-efficiency filters were always the lowest and the greatest, respectively. For Pb and, especially, As, the concentrations in the high-efficiency filters were significantly lower than those in the low-efficiency filters. As described above, high-efficiency filters retain a greater fraction of small particles than low-efficiency filters. On the other hand, low-efficiency filter dust has a greater proportion of larger particles than high-efficiency filter dust. Therefore, the data suggest that large particle size fractions may have greater metal concentrations than small particle size fractions. This observation is in accordance with the findings of Al-Rajhi et al. (1996). However, another study (Lisiewicz et al., 2000) detected higher metal concentrations in fine particles than in larger particles. General conclusions are difficult to draw because of the limited number of sites investigated in the current study and because the filters with different efficiencies were not uniformly distributed throughout the sites and, therefore, some biases due to potential site-specific sources are possible. Furthermore, different metal sources, both indoor and outdoor, may have a significant influence on the metal concentration distribution for particles of different sizes. In our study, Cd concentrations were extremely uniform across filters with different efficiencies and the Cd concentrations detected were comparable to values reported in the literature for settled dust (Jaradat et al., 2004; Momani et al., 2002; Turner et al., 2006). The concentration of As in the low-efficiency filters was greater than those for the mid- and high-efficiency filters, suggesting that the As concentrations in the larger particle size fractions could be particularly elevated. Decker et al. (2002) associated elevated indoor dust levels of arsenic with pressure-treated wood. Table 5. Median Metal Concentrations in the HVAC Filter Dust for Filters with Different Efficiencies Pb Cd As Filter MERV [mu]g/g Low 18.5[+ or -]0.79 2.00[+ or -]0.062 4.61[+ or -]0.24 Mid 12.9[+ or -]0.54 1.64[+ or -]0.035 1.89[+ or -]0.32 High 7.49[+ or -]0.44 1.54[+ or -]0.027 0.912[+ or -]0.22 Table 6 summarizes the mass of metals collected on the HVAC filters, calculated as the metal concentration multiplied by the mass of dust collected on the seven filters where the dust mass was measured. Filter 2 at Site 6 appears to be highly contaminated with all three metals. Metal mass seems to have similar trends for the three metals and it is unusual for a site to have a low concentration of one element and an elevated concentration of another one. Table 7 summarizes the median metal mass on filters with low and mid efficiencies. Mid-efficiency filters collected a higher mass of all three metals analyzed. Filter efficiency data obtained from ASHRAE Standard 52.2 (ASHRAE, 2007) indicates that mid-efficiency filters capture approximately two to three times as many 3.0-10.0 [micro]m particles than the low-efficiency filters. Similar (or even stronger) trends in capture efficiency are also expected for smaller particles and, this difference in removal efficiency could explain the different quantities of metals retained on the filters. Table 6. Metal Mass of HVAC Filters Pb Cd As Site Filter Filter Efficiency Amount of Metal, [mu]g 2 2 Low 11.8 9.09 2.30 [+ or -] [+ or -] [+ or -] 1.6 0.69 2.4 3 2 Mid 3.48 0.882 1.57 [+ or -] [+ or -] [+ or -] 0.18 0.045 0.66 4 1 Low 5.11 0.752 0.407 [+ or -] [+ or -] [+ or -] 0.28 0.033 0.032 5 2 Low 8.51 0.470 3.18 [+ or -] [+ or -] [+ or -] 0.81 0.079 0.14 6 2 Mid 192 22.6 37.4 [+ or -] [+ or -] [+ or -] 33 1.1 2.0 7 2 Mid 53.0 3.80 14.5 [+ or -] [+ or -] [+ or -] 0.92 0.064 0.29 9 2 Mid 36.7 1.51 3.47 [+ or -] [+ or -] [+ or -] 8.7 0.031 0.35 Table 7. Median Metal Mass on HVAC Filters with Different Efficiencies Pb Cd As Filter MERV Amount of Metal, [mu]g Low 8.51[+ or -]0.81 0.752[+ or -]0.079 2.30[+ or -]0.14 Mid 44.9[+ or -]4.8 2.66[+ or -]0.055 8.96[+ or -]0.51 There are several parameters that may play a significant role in the application of HVAC filters as samplers and could potentially represent confounding factors in data interpretation. Further investigation is required to understand the influence of size-resolved filter efficiency, indoor mixing conditions, HVAC system run time, microbial growth and decay in filter dust, and particle-size dependence of the contaminants of interest. Once the impact of these factors is better delineated, HVAC filters may become a useful, widely-available sampling tool that can be collected with minimal effort and analyzed for a broad spectrum of contaminants. CONCLUSION We measured microbial and metal concentrations in HVAC filter dust collected from nine sites. We detected culturable bacterial and fungal concentrations in the [10.sup.5] - [10.sup.7] and [10.sup.4] - [10.sup.6] CFU/g ranges, respectively. Spore concentrations represented a smaller fraction, typically two to three orders of magnitude lower than the total concentrations. The microbial concentrations in the filter dust were slightly higher than settled dust concentrations reported in the literature and are in the same range as those reported for soil. These results indicate that HVAC filters in humid environments such as central Texas represent a hospitable environment for microbial proliferation. Microbial concentrations on filters with different removal efficiencies were relatively similar, typically within one order of magnitude. Mean Pb concentrations in the HVAC filter dust were particularly elevated with mean values as high as 29 [micro]g/g, while Cd and As concentrations were on the order of a few [micro]g/g. 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Siegel is an associate professor and K.A. Kinney is a professor in the Department of Civil, Architectural, and Environmental Engineering, The University of Texas, Austin. |