Mean TSP and SO2 by season and year in Philadelphia, 1974–88
| Year | Summer | Winter | |||||
|---|---|---|---|---|---|---|---|
| TSP (μg/m3) | SO2 (ppb) | TSP (μg/m3) | SO2 (ppb) | ||||
| 1974 | 84 | 20 | 93 | 35 | |||
| 1975 | 75 | 17 | 77 | 26 | |||
| 1976 | 78 | 19 | 83 | 25 | |||
| 1977 | 69 | 16 | 77 | 27 | |||
| 1978 | 74 | 17 | 73 | 25 | |||
| 1979 | 77 | 15 | 68 | 21 | |||
| 1980 | 76 | 14 | 59 | 18 | |||
| 1981 | 66 | 14 | 61 | 20 | |||
| 1982 | 64 | 13 | 56 | 20 | |||
| 1983 | 66 | 10 | 52 | 15 | |||
| 1984 | 65 | 10 | 56 | 18 | |||
| 1985 | 62 | 10 | 54 | 17 | |||
| 1986 | 65 | 8 | 53 | 15 | |||
| 1987 | 70 | 9 | 53 | 15 | |||
| 1988 | 64 | 9 | 52 | 17 | |||