Indoor air sources

Tichenor BA (1989) Indoor air sources using small environmental test chambers to characterize organic emissions from indoor materials and products. US EPA, report no EPA-600/8-89-074... 

As a follow-up to the European Audit project, the Database project (European database on indoor air pollution sources in buildings) was launched to investigate the emissions (sensory and chemical) of indoor air sources, and in particular the building materials, more closely. This resulted in the first database of indoor air pollution sources [28]. 

Fig. 23-1. Representation of home with various sources and sinks for indoor air pollutants (A), exchange (B), indoor concentration (C), outgassing of building and furniture materials (D), irvfiltration from soils (E), removal on interior surfaces.

Table 23-1 shows the major categories of indoor air pollutants and sources. Table 23-2 shows a summary of reported indoor air pollutant concentrations compiled by the U.S. Environment Protection Agency. Infor-... 

Source U S. Environmental Protection Agency Report to Congress on Indoor Air Quality, EPA/400/l-89/001c, August 1989. 

Indoor air contaminants can originate within the building or be drawn in from outdoors. If contaminant sources are not controlled, problems can arise, even if the HVAC system is properly designed and well-maintained. Sources can be from outside the building from operating equipment, from human activities, and other or miscellaneous sources. Sources outside a building include contaminated outdoor air, emissions from nearby sources, soil gas, or moisture or standing water. 

An initial walkthrough of the problem area provides information about all four of the basic factors influencing indoor air quality (occupants, HVAC system, pollutant pathways, and contaminant sources). The initial walkthrough may provide enough... 

Ventilation modification is often used to correct or prevent indoor air quality problems. This approach can be effective either where buildings are underventilated or where a specific contaminant source cannot be identified. Ventilation can be used to control indoor air contaminants by ... 

When you have pursued source control options and have increased ventilation rates and efficiency to the limits of your expertise, you must decide how important it is to pursue the problem further. If you have made several unsuccessful efforts to control a problem, then it may be advisable to seek outside assistance. The problem is probably fairly complex, and it may occur only intermittendy or cross the borders that divide traditional fields of knowledge. It is even possible that poor indoor air quality is not the actual cause of the complaints. Bringing in a new perspective at this point can be very effective. 

Examine your building operation. Make an inventory list of all the sources of contaminants that impact on indoor air quality. Determine whieh among these are likely to have first order effects on air quality. 

The models in the THERdbASE CD are Chemical Source Release, Instantaneous Emission, Chemical Source Release, Timed Application, Indoor Air (2-Zone), Indoor Air (N-Zone), Exposure Patterns for Chemical Agents, Benzene Exposure Assessment Model (BEAM), Source Ba.sed Exposure Scenario (Inhalation + Dermal), and Film Thickness Based Dermal Dose. 

Occupational and environmental exposure to chemicals can take place both indoors and outdoors. Occupational exposure is caused by the chemicals that are used and produced indoors in industrial plants, whereas nonoccupa-tional (and occupational nonindustrial) indoor exposure is mainly caused by products. Toluene in printing plants and styrene in the reinforced plastic industry are typical examples of the two types of industrial occupational exposures. Products containing styrene polymers may release the styrene monomer into indoor air in the nonindustrial environment for a long time. Formaldehyde is another typical indoor pollutant. The source of formaldehyde is the resins used in the production process. During accidents, occupational and environmental exposures may occur simultaneously. Years ago, dioxin was formed as a byproduct of production of phenoxy acid herbicides. An explosion in a factory in... 

Outdoor inhalation exposure is mainly due to traffic, energy production, heating, and natural factors such as pollen and mineral dusts. These outdoor sources of pollution also affect indoor air quality. The indoor concentration is typically 20-70% of the corresponding outdoor concentration. Occasionally the indoor concentrations of an external pollutant (especially radon) may even exceed the concentrations outdoors. ... 

J.B. White, J.C. Reaves, P.C. Reist, and L.S. Mann. A data base on the sources of indoor air pollution emissions. In Engineering solutions to indoor air pollution Proceedings of the ASHRAE Conference lAQ 88, pp. 34-48. ASHRAE, Atlanta, 1988. 

Boundary conditions and thermophysical properties, etc. are clearly specified (e.g., indoor air quality can be predicted only if the location and strength of the sources are known). 

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