Identification and quantification of volatile organic compound emissions from buildings and heating, ventilating and air conditioning systems

Many indoor and outdoor sources release volatile organic compounds (VOCs) that can affect indoor air quality(IAQ). Indoor sources produce VOC concentrations in buildings that often greatly exceed outdoor levels. Since people spend 70-90% of their time indoors, most exposure to VOCs occurs indoors. This exposure is a potential contributor to the complex of sub-chronic health symptoms known as "sick building syndrome".;The objectives of this study were to characterize VOC emissions in buildings, to evaluate approaches for apportioning the emissions among major sources, and to explore relationships between VOC measurement techniques. VOC emissions from building materials and furnishings, occupants, and heating ventilation and air conditioning (HVAC) systems were estimated using a mass balance approach, measurements of total VOC (TVOC) concentrations using flame ionization detection, and speciated VOC (SVOC) measurements using canister samples, cryogenic preconcentration, gas chromatography and mass spectrometric detection. Three HVAC systems in two office buildings were tested over two seasons. Sorption characteristics of HVAC filters and filter dust were investigated separately in chamber tests.;SVOC concentrations in the case study buildings ranged from 1.0 to 146 ;Occupants and their activities were important VOC sources in both buildings resulting in TVOC emissions of 2-3 g/hr during work hours. Building-related emissions were not significant in one building, but were much higher (6.1 g/hr) in the other building. These emissions appeared to result from building materials and printed matter stored in the building. Although some field measurements indicated strong sorption of toluene by HVAC filters and dust, this was not confirmed in laboratory chamber tests using toluene and trichloroethylene and these substrates. Sorption effects in HVAC systems may be more significant for low volatility compounds. Overall, HVAC emissions were not significant.;The mass balance model using VOC measurements collected in HVAC systems can provide reliable estimates of indoor emissions if air in interior spaces is relatively well-mixed. The approach is especially suited to sealed buildings with single air handling systems. It provides building-wide estimates that apportion indoor concentrations to outdoor and several indoor sources, information that can be used to help improve IAQ.