Indoor air levels

In areas of agricultural methyl parathion usage, both outdoor and indoor air levels of methyl parathion of approximately 12 ng/m have been measured, and household dust was found to contain 21 ppb of methyl parathion. Outdoor and indoor air concentrations of methyl parathion as high as 0.71 and 9.4 pg/m, respectively, have been measured at the homes of individuals employed as pesticide formulators. 

Trichloroethylene levels monitored in expired breath of 190 New Jersey residents were correlated with personal exposure levels, which were consistently higher than outdoor air levels and were instead attributed to indoor air levels (Wallace et al. 1985). Other studies have expanded upon and confirmed these findings, concluding that indoor air is a more significant exposure source of trichloroethylene than outdoor air, even near major point sources such as chemical plants (Wallace 1986 Wallace et al. 1986a, 1986b, 1986c,... 

As a result of volatilization, significantly elevated indoor air levels of trichloroethylene can occur in homes that use water supplies contaminated with trichloroethylene (Andelman 1985a). The transfer of trichloroethylene from shower water to air in one study had a mean efficiency of 61% which was independent of water temperature (McKone and Knezovich 1991). The study authors concluded that showering for 10 minutes in water contaminated with trichloroethylene could result in a daily exposure by inhalation comparable to that expected by drinking contaminated tap water. Another study using a model shower system found that, in addition to shower spray, shower water collecting around the drain could be an important source of volatilized trichloroethylene, and the fraction volatilized could be affected by spray drop size and flow rate (Giardino et al. 1992). 

Inhalation is the predominant route of exposure to 1,4-dichlorobenzene for the general population. According to data from the TEAM study, 1,4-dichlorobenzene was found in 44-100% of air and breath samples from several U S. locations, and indoor air levels were up to 25 times higher than ambient outdoor levels for dichlorobenzene (1,3- and 1,4-dichlorobenzene) (Wallace et al. 1986b). The EPA has estimated that adult exposure to 1,4-dichlorobenzene is about 35 g/day, based on a mean ambient air concentration of 1.6 g/m (0.27 ppb) (EPA 1985a). Inhalation exposure may be considerably higher indoors where 1,4-dichlorobenzene space deodorants or moth repellents are used. 

Moschandreas, D. J., and D. S. O Dea, Measurement of Per-chloroethylene Indoor Air Levels Caused by Fugitive Emissions from Unvented Dry-to-Dry Dry Cleaning Units, J. Air Waste Manage. Assoc., 45, 111-115 (1995). 

DEHP levels in indoor air might be higher due to stow volatilization from plastic products (EPA 1981 Warns 1987). As noted in Section 6.2.1, Cadogan et al. (1994) reported that an indoor overall emission rate of 2.3x10 4 mg/second-m2 at 25 °C has been calculated for all phthalate plasticizers in products such as wall coverings, flooring, upholstery, and wire insulation. The air from rooms recently covered with polyvinyl chloride (PVC) tiles contained 0.15 0.26 mg/m3 (150,000 260,000 ng/m3) phthalate esters (EPA 1981). Indoor air levels in rooms with new flooring couldbe about 0.2 0.3 mg/m3 (Warns 1987). 

The influence of the volatility of a pesticide on measurable indoor air levels is evident by comparing semivolatile chlorpyrifos with nonvolatile permethrin. Room-air concentrations of these two insecticides were found to be comparable (means of 30 and 42p.g/m, respectively) 0-2h after broadcast spraying, but the air levels of permethrin declined so rapidly that nothing ([Pg.109]

Patterson, 1991). Indoor air levels of chlorpyrifos applied as a microencapsulated formulation were measured at 3.1p,g/m 0-2 h after broadcast spraying and 5.2 p,g/m after 24h, compared to 30 and 15 p.g/m, respectively, for the emulsi-liable concentrate (Koehler and Moye, 1995a). After 48 h, levels were still about double for the emulsifiable concentrate application (8.5 p-g/m versus 4.0 pg/m ). 

However, on an empirical basis, the range of potential emission behavior is reasonably well known, and the correlation between emission measurements on product samples under standard conditions can now be related well to the expected range of indoor air levels under various user conditions. This subject is discussed in two separate chapters. Thus, quality control depends on formaldehyde emission measurements. This can be done by determination of the formaldehyde content of the finished product, or by measuring air levels around the product. 

Since moisture equilibration, i.e. "conditioning of wood is a slow process that may require a week or longer depending on product thickness, and since temperature adaptation lags by at least an hour, the emission from wood products is not always at equilibrium. This fact has caused non-technicaI people to incorrectly distrust product performance. However, it has been found that the emission directly reflects the daily temperature cycles of outside wails (52). Thus, mobile home placed in a warm climate, indoor air levels may change by a factor of 6 or more during a This is shown in Figure 1. 

Progress in quality control and in basic understanding of the physical and chemical factors affecting formaldehyde emission processes have made it possible to predict formaldehyde indoor air levels for most use conditions. Progress in manufacturing techniques and implementation of new technology have reduced formaldehyde emission so much that UF-bonded wood products can now be used in almost all applications without indoor air concentrations exceeding 0.I pp. 

The incidence of perceptible formaldehyde in homes, offices and schools has caused widespread uncertainty about the safety of living with formaldehyde. This uncertainty was enhanced by the large scale installation of urea formaldehyde foam insulation (UFFI) because a substantial part of this material was made from small scale resin batches prepared under questionable quality control conditions, and was installed by unskilled operators (10). The only reliable way to avoid such uncertainty is to know the emission rate of products and develop a design standard that allows prediction of indoor air levels. The first and most important step in this direction was achieved with the development and implementation of material emission standards. As indicated above, Japan led the field in 1974 with the introduction of the 24-hr desiccator test (6), FESYP followed with the formulation of the perforator test, the gas analysis method, and later with the introduction of air chambers (5). In the U.S. the FTM-1 (32) production test and the FTM-2 air chamber test (33) have made possible the implementation of a HUD standard for mobile homes (8) that is already implemented in some 90% of the UF wood production (35), regardless of product use. 

The test results can be used to predict indoor air levels if load factors, ventilation rates, temperature, air humidity and occupant activities are known. This subject is explained in Chapter 1. By way of example. Figure 2 shows the safe product range that has been established in Sweden for particelboard use in conventional housing (14). As soon as product performance is widely disclosed and builders and architects become familiar with the product ratings, formaldehyde complaints will rapidly decrease and likely become a thing of the past. 

Oatman L, Roy R. 1986. Surface and indoor air levels of polychlorinated biphenyls in public buildings. Bull Environ Contain Toxicol 37 461-466. 

Based on testing with FLEC, indoor air levels of material-specific compounds can be estimated in a room assuming no sinks. A worst case approach with a 17-m standard room (INF, 1994) is applied for the purpose of health and comfort evaluation of building products and materials in the Danish Labeling Scheme (Wolkoff and Nielsen, 1996 Larsen 1997). 

Fenske RA, Stembach T. 1987. Indoor air levels of chlordane in residences in New Jersey. Bull Environ Contam Toxicol 39 903-910. 

Ao, C.H., and S.C. Lee, Combination effect of activated carbon with TiOj for the photodegradation of binary pollutants at typical indoor air level.. 1. Photochem. Photohiol. 4. 161 (2004) 131-140. 

OPEs) are iDdoor air coDtaminants (Rudel et al. 2003). Levels of APs in household dust and air were monitored in 120 homes located in Cape Cod, Massachusetts. Median levels of 4-NP were 110 ng/m in indoor air and 2.58 pg/g in dust samples, while median levels of mono-NPE and mono-OPE were 17 and 8.6 ng/m, respectively, in air. Median AP and APE levels were below 6 pg/g in dust samples. In a California-based study conducted several years later, median household indoor air levels of 4-tcrt-NP were half (53.0 ng/m ) (Rudel et al. 2010) of levels detected on Cape Cod (Rudel et al. 2003), reflecting either different usage patterns or changes in formulation of products with NP. Median indoor air levels of NP in the Rudel et al. (2010) California study were similar to those previously reported by Satio et al. (2004) for Japanese households. 

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