Air Quality Profile of Inorganic Ionic Composition of Fine Aerosols at Two Sites in Mumbai City

The levels of PM 10 , PM 2.5 , and NO 2 were studied at a kerbsite and ambient site in Mumbai. Measurements were also made for eight inorganic ions (F − , Cl − , NO 3 − , SO 2− 4 , Na + , K + , NH 4 + , Ca 2+ , and Mg 2+ ) in the PM 2.5 fraction. During the study period, PM 2.5 , PM 10 and NO 2 levels ranged between 11–91, 18–125, and 8–64 μ g m − 3 at a ambient site whereas at the kerbsite the ranges were 10–176, 21–189, and 4–55 μ g m −3 respectively. Average PM 2.5 values were 42 μ g m − 3 at ambient and 69 μ g m −3 at the kerbsite. The measured ions accounted for about 50% of the PM 2.5 mass. Non-sea-salt (nss) sulfate contributed 91% and 85% of the ionic mass at the ambient and kerbsite sites respectively. Due to biomass sources of K, only about 5% of K + was from seas salt. The average equivalent ratio of NH 4 + to nss- SO 2 4 − , and NO 3 − was over 1, indicating high source strength of ammonia.