• The PM2.5 decreased in response to the sulfate decrease.

• Sulfate has been implicated as a major toxic species in PM2.5 (Amdur 1996) and reported to be associated with increased risk of various mortality outcomes in earlier epidemiological studies

• Variation with site and stack height is weaker in the case of ozone and much weaker in the case of sulfate and nitrate aerosols, because these pollutants are formed only gradually over tens (for ozone) to hundreds (for nitrates and sulfates) of kilometres from the source.