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This article describes common indoor air pollutants and explains how to remove them.
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Common Indoor Air Pollutants & How to Remove Them
Table at page top and accompanying text are reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Readers looking for a thorough, detailed guide to improving indoor air quality should also see INDOOR AIR QUALITY IMPROVEMENT GUIDE. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. [Click to enlarge any image including the page top table]
How to Remove indoor air contaminants including: allergens, formaldehyde gas, radon gas, particulates such as smoke, soot, carbon monoxide, carbon dioxide, nitrogen dioxide, organic compounds, asbestos, and improved make-up air in buildings.
The following key articles provide in-depth information about indoor air contaminant detection, effects, testing, and remediation or removal.
ALLERGEN TESTS for BUILDINGS discusses the detection of allergenic particles indoors, such as animal dander, hair, cockroach and insect fragments, dust mites, mite fecals, etc.
Asbestos Hazards as well as other indoor air quality topics listed in detail at the end of this article .
BIOLOGICAL POLLUTANTS such as mold, animal dander, cat or dog dander, mouse dander or droppings, animal hair, cockroaches, dust mites, dust mite fecal pellets
Formaldehyde & Radon Reduction Indoors - a PDF article: "Breathing Free, Part I: how to do battle with formaldehyde and radon in houses", (use your browser's back button to return to this article series). This article discusses how to reduce formaldehyde-using products in buildings.
Radon gas and radon in water hazards in buildings - list of key Radon articles is given below
This article series, originally by Steven Bliss and appearing in Solar Age Magazine, explains Indoor Air Pollutants & How to Remove Them, including indoor air contamination by allergens, formaldehyde gas, radon gas, particulates such as smoke, soot, carbon monoxide, carbon dioxide, nitrogen dioxide, organic compounds, asbestos, and improved make-up air in buildings.
Sources of Formaldehyde in Buildings & Formaldehyde Exposure Effects
High levels of formaldehyde gas indoors can cause eye and respiratory irritation, and can cause headaches and dizziness. Long term exposure to formaldehyde may cause respiratory-tract harm and can trigger asthma attacks in susceptible individuals. Previous cancer-concerns associated with formaldehyde offgassing from UFFI insulation were discounted by subsequent research.Formaldehyde can cause eye, nose and throat irritation, and has been identified as a human cancer-causing agent (IARC, 2004/2009). As early as 1984 ASHRAE reported as a standard a "comfort level" of indoor formaldehyde gas as 0.1 ppm.
Formaldehyde was used and continues to be used in many building products, coatings, finishes, and furnishings because it has desirable chemical properties and is inexpensive. Nearly all products made using formaldehyde outgas to some extent, some completely, so that the level of this irritating gas is usually substantially reduced or eliminated over time with little or no consumer action.
Of chief concern, probably because their outgassing lasts longer, are wood products made with urea formaldehyde (UF) glues, including most hardwood plywoods, decorative paneling, and nearly all particle board materials. On the other hand, nearly all softwood plywoods use phenol formaldehyde adhesives that are more chemically stable and that have negligible formaldehyde emissions.
See FORMALDEHYDE HAZARDS for a table of "Common Concentrations of Formaldehyde (HCHO) in Indoor & Outdoor Air " - formaldehyde levels found outdoors and in buildings and a comparison of those levels with current residential exposure standards for formaldehyde.
Also see these research articles on formaldehyde sources in buildings
Bissett, John. "Fungi associated with urea-formaldehyde foam insulation in Canada." Mycopathologia 99, no. 1 (1987): 47-56.
Sixty-eight fungal taxa were identified from samples of urea-formaldehyde foam insulation taken from Canadian residences. Mesophilic taxa were predominant, with Penicillium spp., Trichoderma harzianum and Paecilomyces variotii observed most frequently. Extensive or conspicuous growth also was seen for Hormoconis resinae, Stachybotrys chartarum and Trichoderma viride in some samples. The potential for these fungi to have contributed to the adverse health effects reported in some homes containing UF-foam insulation is discussed.
Excerpt 1: High temperatures and humidity accelerate deterioration of UFFI, leading
to breakage of the foam cell walls and shrinkage of the foam .
Excerpt 2: Although off-gassing was initially thought the probable cause of the reported adverse health effects in some UFFI homes, studies to date do not show a clear correlation between adverse symptoms and the concentratio nof off-gases from foam insulation. Consequently, other facctors associated with UFFI, including the presence of fungi, have been investigated as concomitant causes of tehse adverse health symptoms.
Guo, H., N. H. Kwok, H. R. Cheng, S. C. Lee, W. T. Hung, and Y. S. Li. "Formaldehyde and volatile organic compounds in Hong Kong homes: concentrations and impact factors." Indoor Air 19, no. 3 (2009): 206-217.
Hodgson, A. T., D. Beal, and J. E. R. McIlvaine. "Sources of formaldehyde, other aldehydes and terpenes in a new manufactured house." Indoor Air 12, no. 4 (2002): 235-242.
Järnström, H., K. Saarela, P. E. a1 Kalliokoski, and A-L. Pasanen. "Reference values for indoor air pollutant concentrations in new, residential buildings in Finland." Atmospheric Environment 40, no. 37 (2006): 7178-7191.
Kim, Sumin, and Hyun‐Joong Kim. "Comparison of formaldehyde emission from building finishing materials at various temperatures in under heating system; ONDOL." Indoor Air 15, no. 5 (2005): 317-325.
Wieslander, G1, D. Norbäck, E. Björnsson, C. Janson, and G. Boman. "Asthma and the indoor environment: the significance of emission of formaldehyde and volatile organic compounds from newly painted indoor surfaces." International archives of occupational and environmental health 69, no. 2 (1996): 115-124.
Yu, Chuck, and Derrick Crump. "A review of the emission of VOCs from polymeric materials used in buildings." Building and Environment 33, no. 6 (1998): 357-374.
Radon Gas in Building Air and Water - Sources & Exposure Effects
Radon is an odorless, colorless gas that occurs naturally as a byproduct of the decay of uranium. In parts of the world where uranium-bearing rock is present under buildings, this gas can in some (not all) instances seep into buildings where the enclosed character of the building leads to a higher level of radon than would be found outdoors.
At higher levels radon gas is a lung cancer hazard, especially to people who smoke (who have an 80-times greater risk than non-smokers).
See Radon Enviro-Scare for a full discussion of the normal cycle of public fear that accompanies the discovery and publicity of various environmental hazards, including radon gas and see Enviro-Scare, the Cycle of Public Fear for our article about consumer environmental safety worry cycles that change over time.
For a Thorough Background in Radon Hazards, Radon Mitigation, & the History of Radon Concerns in the U.S. also see these articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
"Defeating Radon" part 1 - Terry Brennan, Bill Turner, Solar Age Magazine - How does radon get into buildings, how do I know if a building has a radon gas problem, how can I solve radon problems in existing homes, and what can I do to prevent radon from entering new homes. Part 1: where Radon comes from, how to diagnose radon
Other Sources of Common Indoor Air Pollutants or Contaminants
Basic checks for sources of common indoor air contaminants in buildings: Here and in detailed articles whose links are found at the end of this article , we provide air contamination troubleshooting help for buildings by expanded annotated information from the US EPA  who suggested common air pollutant sources to be considered during an indoor air quality investigation.
Outside sources of air pollution that may impact indoor air quality under some conditions include
airborne pollen, dust, or fungal (mold) spores; The levels of these particles in outdoor air and thus potentially in indoor air vary widely by season, proximity to source, and building air handling and ventilation equipment design. and use.
Vehicle emissions, particularly near highways, urban centers, and locations where vehicles may be left idling for long periods such as loading docks
Air pollution sources nearby to buildings where indoor air quality complaints are observed include:
garbage container odors such as nearby dumpsters
Unsanitary debris or building exhausts (cooking, bath, industrial) near building outdoor "fresh air" intake openings
Underground sources of air pollution in or around buildings
Underground oil storage tanks or other fuel storage tanks
Sewage backups, septic tank leaks, septic drainfield failures
Building HVAC equipment sources of indoor air pollution
Mold or bacterial growth in condensate drip pans, ductwork, cooling coils, and humidifiers
Chimney flue and vent defects that spill combustion products in the building
Dust, debris, rodents, mold, or prior flooding in the HVAC system ductwork
Building equipment sources of indoor air contaminants
Office equipment such as copiers that may spill inks, toners, ozone, VOCs
Shops, labs, cleaning processes that emit contaminants; we have traced severe building odor complaints to a beauty parlor at one of the building whose HVAC system was transporting odors throughout the structure
Building components/furniture/furnishings as sources of indoor air quality complaints or contaminants
microbial growth in or on soiled or water damaged materials such as carpeting or furniture
Dry plumbing traps permitting sewer gases to escape into the building
Materials in furnishings that emit VOCs, inorganic compounds, or asbestos particles (from damaged asbestos insulation or asbestos-containing products
Furnishings such as furniture or flooring that may emit odors from glues, sealants, paints, foam cushions, particleboard
Other common indoor air pollution or IAQ complaint sources in buildings including homes & schools
Sewage backups, toilet overflows
Vocational arts areas
Copy or printing centers
Food preparation areas
Cleaning materials stored in or near areas of complaints
Trash and garbage odors
Pesticides sprayed or placed in or around the building
Odors and VOCs from paints, chalks, adhesives used in the building
Occupants who suffer from communicable diseases
Dry-erase markers and pens
Insect infestation, or other building pests such as rodents, feral cats, raccoons, squirrels birds
Personal care products
Ventilation to Improve Indoor Air Quality
While avoiding use of outgassing products to reduce formaldehyde gas indoors and sealing cracks or installing a radon mitigation system is effective in eliminating indoor radon gas hazards, the soup of indoor irritants and pollutants can also be effectively thinned by good building ventilation.
Doubling the rate of fresh air intake in a building will in general cut most indoor air pollutant levels in half. (This might not be true for pollen levels in some locations in some seasons where air conditioning or air filtration will be a better bet.)
Mr. Bliss's article interestingly points out that the level of indoor air contaminants varies among buildings by a factor of 100, so don't make an assumption about what your home needs without more careful study.
Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.
AIHA, American Industrial Hygiene Association, “Is Air Quality a Problem in My Home?”,
IARC, 2009. IARC classifies formaldehyde as carcinogenic to humans; press release no.153; International Agency for Research on Cancer: Lyon.
Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: email@example.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
Roger Hankey is principal of Hankey and Brown home inspectors, Eden Prairie, MN. Mr. Hankey is a past chairman of the ASHI Standards Committee. Mr. Hankey has served in other ASHI professional and leadership roles. Contact Roger Hankey at: 952 829-0044 - firstname.lastname@example.org. Mr. Hankey is a frequent contributor to InspectAPedia.com.
Arlene Puentes, an ASHI member and a licensed home inspector in Kingston, NY, and has served on ASHI national committees as well as HVASHI Chapter President. Ms. Puentes can be contacted at email@example.com
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Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
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