Title: Characterization of ambient, indoor, and personal PM exposures in a NYC panel study

Particulate matter (PM) time-series analyses have found associations of ambient PM mass concentrations at central-monitoring-sites (CMS) with adverse health endpoints. Major uncertainties that arise from this approach are whether personal exposure to PM can be adequately represented by central site mass concentrations.

Concurrent 24-hr CMS, residential outdoor, residential indoor, and personal PM10 and PM2.5 measurements were made for a panel of 9 COPD patients in NYC. Each participant was followed for 12-consecutive day during summer and winter seasons (2000-2001). Total PM mass and chemical constituents were analyzed via gravimetric and XRF analyses, respectively. Temporal, spatial distribution and correlations of different PM sizes and compositions were investigated for each sample type.

We found considerably higher PM10 personal exposures as compared to the co-located indoor and ambient concentrations (both from CMS and residential outdoor). The composition of indoor, outdoor, and personal PM10 samples differed, with soil elements (Si, Ca) higher in indoor and personal samples than in ambient samples. In contrast, secondary sulfur and combustion-related elements (Ni, elemental carbon) were higher in ambient rather than in indoor samples. Seasonal and spatial trends showed different patterns for each of the constituents. Personal PM10 concentrations were highly correlated with indoor and outdoor concentrations for a combustion element (r=0.7 for S), whereas poor correlations were found for the crustal elements (r=0.4 for Si).

The high personal-ambient S correlation indicates that it is a good tracer for ambient fine PM exposure and hence supports the use of CMS measurements in epidemiological studies.