Correlation of the blackness index of high volume air samples with the polycyclic hydrocarbon concentrations in urban air.

The blackness index of an air sample, measurea by reflectance on an air sample filter, is an indication of the mean darkness of the particles collected on such a medium. As the presence of polycyclic hydrocarbons in air samples is associated with soot or carbon particles, it seemed reasonable to find out if a correlation between these two measurements could be established. The current availability of analytical methods of sufficient sensitivity allowed us to make accurate measurements of the two hydrocarbons. The polycyclic levels found were then compared with the measurements of particular matter and the blackness index to discover the best correlation. These correlations have been established for air samples from three different North American cities, and for different stations within the cities.