1 Pesticides  Tens of millions of pounds of pesticides are used in homes, buildings, and gardens annually: for example, pesticides used in lawn care currently account for about 70 million pounds of active ingredients in the United States yearly  pesticide chemicals are also used to impregnate strips, in foggers, direct application sprays, or in powder form  most pesticides have inherently toxic ingredients that must be stored and used properly: in an EPA survey (1987), only 9% of the respondents actually read labels and used pesticide-containing products with caution  in addition to direct exposure during use, secondary exposure can occur: lawn maintenance can aerosolize pesticides with drift indoors; similarly pesticides sprayed onto school playing fields drift into buildings, air intakes, and become resuspended during use or direct contact.

2 Formaldehyde  Formaldehyde, used in hundreds of products, is one of the most ubiquitous indoor organic vapors, and is added to medicines, cosmetics, toiletries, and some food containers as a preservative  The largest single use of formaldehyde is in producing urea and phenol formaldehyde resins, which are used to bond laminated wood products and to bind wood chips in particleboard  these wood products are widely used in homes and offices, as shelving, counters, bookcases, cabinets, floors, and wall covers  In the mid-1970s, urea formaldehyde foam insulation (UFFI) became a popular insulation material. UFFI emits formaldehyde in an initial burst and then continuously at a lower level. Improper installation or formulation results in a sustained release and higher formaldehyde concentrations indoors.

3 Volatile Organic Compounds (VOCs)  A variety of furnishings, particularly those containing synthetic materials, can contribute to indoor air pollution  Wall-to-wall carpeting, often glued to the floor with adhesives, and draperies made of synthetic fibers can be the source of a variety of volatile chemicals  Organic dust and fibrous glass particles can arise from deteriorating foam cushions and curtains  Furniture constructed with particleboard can emit formaldehyde  Office equipment can emit a large number of pollutants  photocopying machines may release ozone and VOC  Small office refrigerators and heat pumps may become defective and leak chlorofluorohydrocarbons  Blueprint machines may release ammonia, and photographic equipment may release acetic acid.

4 Microbiologic Contaminants  Indoor microbiologic contaminants take a wide variety of forms  pollen from trees, grasses, and other plants may infiltrate from outdoors  contaminants of indoor origin include viruses, bacteria, fungal spores, protozoa, algae, animal dander and excreta, and insect excreta and fragments  volatile metabolites of living and decaying organisms should also be considered  the contaminants may be viable organisms that multiply in an infected host, or the organisms may live in dust, soil, water, oil, organic films, food, vegetative debris, or wherever the micro-climate provides conditions that support growth  for example: bathroom walls and window casements as well as damp basements are sites where water condenses

5 Indoor Allergens

6 Radon  Radon-222, a noble gas, is produced in the decay of naturally occurring uranium-238. Its half-life is 3.8 days, and it decays into a series of short-lived progeny: polonium-218, lead-214, bismuth-214, and polonium-214, all of which have a half-life shorter than 30 minutes.  The principal source in buildings is natural radon gas in soil.  The soil gas penetrates through sump pump wells, drains, cracks, utility access holes, and foundations into the air in homes.  The driving pressure for entry of soil gas comes from the pressure gradient established across the soil by a house and the subflooring; this gradient varies with atmospheric pressure, wind flow over a structure, and buoyancy of air within the structure.  Estimated an average concentration of radon in U.S. homes is 1.5 pCi/L. The distribution of levels is approximately log-normal, about 1 to 3% of homes being above 8 pCi/L. Recommended remediation level is 4 pCi/L.

7 Health Effects of Indoor Air Pollutants  Building-Related Illnesses: These illnesses comprise distinct clinical entities linked to specific etiologic agents.  The types of building-related illnesses include hypersensitivity pneumonitis, asthma, Legionnaire's disease, influenza, and carbon monoxide poisoning.  Symptoms of building-related illnesses have toxic, allergic, or infectious manifestations that can be identified by the physician and often confirmed by the clinical laboratory.  At times, specific etiologic agents can also be identified in buildings.  Resolution of the problem typically involves removal of the source of the problem rather than increasing the ventilation.

8 Health Effects of Indoor Air Pollutants  Sick Building Syndrome: SBS has been identified generally when a substantial number of individuals in a particular building or a portion of the building complain of a diffuse, but often common set of symptoms.  These symptoms, though nonspecific in isolation, form a recognizable pattern that has been repeatedly observed in connection with the sick building syndrome  The common symptoms include eye, nose, and throat irritation, headache, recurrent fatigue, drowsiness, or dizziness, and reduced powers of concentration.  Most individuals report relief of symptoms on leaving the workplace and a recurrence on reentry.

9 Building Related Illnesses

10 Health Effects of Indoor Air Pollutants  The California Healthy Building Study evaluated the relationships between a worker's health symptoms and several building, workspace, job, and personal factors.  The prevalence of eye, nose, or throat irritation was the highest (40.3%), compared to fatigue/sleepiness (33.2%), headache (19.8%), dry/itchy skin (10.8%), chest tightness (7.5%), or chills/fever (4.5%).  Symptom prevalences varied substantially among buildings: the results of this cross-sectional study of 12 office buildings suggested that the occupants of the mechanically ventilated and air-conditioned buildings had significantly more symptoms than those of the naturally ventilated buildings  The increased prevalence rates of some symptoms were associated with the presence of carpet, increased use of carbonless copy paper and photocopiers, space sharing, and distance from a window  These results are consistent with findings that have been widely reported in other studies