PM10 (ug/m3) 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Max. 24-Hour Concentration 289 271 475 179 649 231 161 219 162 227 116 183 Max. Annual Geometric Mean 81.8 81.3 66.9 65.5 62.4 58.0 56.0 51.8 52.0 56.3 43.3 64.9 Calc Days Above State 24-Hr Std 306 300 276 246 234 252 246 228 255 246 186 258 Calc Days Above Nat 24-Hr Std 30 33 18 12 12 18 6 24 6 6 0 6