Polycyclic aromatic hydrocarbons in residential air of ten Chicago area homes: Concentrations and influencing factors

Indoor and outdoor air samples at 10 non-smoker homes in the Chicago area were concurrently collected once per month for a 14-month period starting June 2000. During each sampling event, temperature, humidity, CO2, and CO were recorded. Questionnaires were used to register household activities. For each sample, 16 polycyclic aromatic hydrocarbons (PAHs) were measured using gas chromatograph and mass spectrometer (GC/MS). The total concentration of the 16 PAHs (ΣPAHs) ranged from 13 to 2454 ng m−3 in the indoor air and from 13 to 1865 ng m−3 in the outdoor air. In most cases, the concentrations were found to be log-normally distributed. The sum of PAHs with molecular mass 202 (ΣLight-PAHs, excluding naphthalene and anthracene) were found to behave differently than the sum of those with molecular mass 228 (ΣHeavy-PAHs). Variations among seasons were significant for indoor ΣLight-PAHs, and temperature was found to positively correlate with indoor ΣLight-PAHs for nine of the 10 homes. For ΣHeavy-PAHs, the outdoor concentrations were found to be significantly higher in the fall and winter seasons than in the summer. The correlations of indoor and outdoor concentrations appear to be weak for light PAHs, but reasonably strong for heavy PAHs. The medians of indoor-to-outdoor ratio (I/O) are less than or very close to 1 for all PAHs except anthracene. The indoor concentrations of ΣPAHs tend to be higher as the age of the houses increases, and the surrounding industrial pollution was found to have impact on outdoor ΣHeavy-PAHs. For light PAHs indoors, comparison among homes indicates that the impact of house characteristics and indoor activities tends to be greater than the influence of the penetrating outdoor air.