Measuring reflectance of TSP-filters for retrospective health studies

We measured the reflectance of 174 TSP filters from an air quality study to determine whether the blackness of the filters (an indication of incomplete combustion) could be used as an additional measure of particulate air pollution in retrospective health studies. It is important in health studies to differentiate soil-derived coarse particles from combustion-derived particles. Reflectance was measured with a monochromatic reflectometer and absorption coefficients were derived from the reflectance values using the ISO formula for black smoke absorption coefficients. In the urban setting, the absorption coefficients for TSP filters were associated with black carbon (r=0.89), black smoke absorption coefficients (r=0.9), and gaseous, traffic-related pollutants (r for NO2=0.84), which were measured recently at the same location. Measuring the reflectance of TSP filters is a useful method to estimate the relative concentration of combustion-derived particulate matter in a subarctic winter climate. This method could be useful in retrospective health studies.