Table A-1. National Air Quality Trends Statistics for Cirteria Pollutants, 1989-1998 Statistic # of Sit Units Percentile 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 Carbon Monoxide 2nd Max. 8-hr. 363 ppm 95th 10.9 10.5 9.8 8.5 8.0 8.1 7.6 7.4 6.7 6.3 2nd Max. 8-hr. 363 ppm 90th 9.7 8.8 8.7 7.8 7.2 7.6 6.6 6.5 5.9 5.7 2nd Max. 8-hr. 363 ppm 75th 7.7 7.0 7.0 6.4 5.9 6.2 5.5 5.1 4.9 4.6 2nd Max. 8-hr. 363 ppm 50th 5.9 5.4 5.2 4.8 4.7 4.9 4.3 3.9 3.8 3.5 2nd Max. 8-hr. 363 ppm 25th 4.4 4.2 3.9 3.7 3.6 3.8 3.3 3.0 2.9 2.7 2nd Max. 8-hr. 363 ppm 10th 3.4 3.1 3.0 2.8 2.9 2.8 2.5 2.3 2.1 2.1 2nd Max. 8-hr. 363 ppm 5th 2.6 2.5 2.3 2.4 2.2 2.2 2.3 2.0 1.7 1.9 2nd Max. 8-hr. 363 ppm Arith. Mean 6.2 5.8 5.6 5.2 4.9 5.1 4.5 4.2 3.9 3.8 Lead Max. Qtr. AM 189 ppm 95th 0.27 0.35 0.21 0.18 0.18 0.14 0.14 0.13 0.12 0.13 Max. Qtr. AM 189 ppm 90th 0.17 0.16 0.15 0.13 0.11 0.10 0.09 0.09 0.09 0.08 Max. Qtr. AM 189 ppm 75th 0.11 0.09 0.07 0.06 0.06 0.05 0.05 0.04 0.04 0.04 Max. Qtr. AM 189 ppm 50th 0.06 0.05 0.04 0.04 0.03 0.03 0.03 0.02 0.02 0.02 Max. Qtr. AM 189 ppm 25th 0.03 0.03 0.03 0.02 0.02 0.02 0.02 0.01 0.01 0.01 Max. Qtr. AM 189 ppm 10th 0.03 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Max. Qtr. AM 189 ppm 5th 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 Max. Qtr. AM 189 ppm Arith. Mean 0.09 0.09 0.07 0.06 0.05 0.05 0.04 0.04 0.04 0.04 Nitrogen Dioxide Arith. Mean 225 ppm 95th 0.043 0.040 0.043 0.038 0.037 0.040 0.039 0.037 0.034 0.035 Arith. Mean 225 ppm 90th 0.035 0.034 0.033 0.033 0.033 0.034 0.032 0.032 0.031 0.031 Arith. Mean 225 ppm 75th 0.027 0.025 0.025 0.024 0.024 0.024 0.023 0.024 0.022 0.023 Arith. Mean 225 ppm 50th 0.020 0.019 0.019 0.018 0.018 0.019 0.019 0.018 0.018 0.018 Arith. Mean 225 ppm 25th 0.013 0.013 0.012 0.013 0.013 0.013 0.012 0.012 0.012 0.012 Arith. Mean 225 ppm 10th 0.007 0.007 0.007 0.007 0.007 0.008 0.007 0.007 0.007 0.006 Arith. Mean 225 ppm 5th 0.005 0.005 0.005 0.005 0.005 0.005 0.005 0.004 0.004 0.004 Arith. Mean 225 ppm Arith. Mean 0.021 0.020 0.020 0.019 0.019 0.020 0.019 0.019 0.018 0.018 Ozone 2nd Max. 1-hr. 661 ppm 95th 0.171 0.170 0.170 0.160 0.150 0.150 0.150 0.144 0.142 0.154 2nd Max. 1-hr. 661 ppm 90th 0.150 0.146 0.149 0.131 0.138 0.130 0.139 0.127 0.130 0.134 2nd Max. 1-hr. 661 ppm 75th 0.124 0.120 0.124 0.111 0.120 0.117 0.123 0.114 0.116 0.119 2nd Max. 1-hr. 661 ppm 50th 0.107 0.107 0.108 0.100 0.104 0.104 0.110 0.103 0.103 0.109 2nd Max. 1-hr. 661 ppm 25th 0.095 0.095 0.095 0.090 0.091 0.092 0.098 0.093 0.091 0.096 2nd Max. 1-hr. 661 ppm 10th 0.085 0.083 0.081 0.081 0.080 0.083 0.085 0.085 0.081 0.086 2nd Max. 1-hr. 661 ppm 5th 0.080 0.075 0.075 0.074 0.075 0.077 0.078 0.079 0.075 0.076 2nd Max. 1-hr. 661 ppm Arith. Mean 0.114 0.112 0.113 0.105 0.108 0.107 0.112 0.106 0.105 0.110 4th Max. 8-hr. 661 ppm 95th 0.117 0.116 0.116 0.107 0.110 0.106 0.112 0.103 0.105 0.110 4th Max. 8-hr. 661 ppm 90th 0.105 0.106 0.109 0.097 0.100 0.098 0.106 0.097 0.101 0.102 4th Max. 8-hr. 661 ppm 75th 0.093 0.094 0.097 0.087 0.090 0.090 0.096 0.090 0.091 0.095 4th Max. 8-hr. 661 ppm 50th 0.083 0.083 0.085 0.079 0.081 0.082 0.088 0.083 0.082 0.087 4th Max. 8-hr. 661 ppm 25th 0.075 0.075 0.073 0.073 0.073 0.074 0.077 0.075 0.074 0.077 4th Max. 8-hr. 661 ppm 10th 0.067 0.066 0.065 0.066 0.063 0.067 0.067 0.068 0.065 0.069 4th Max. 8-hr. 661 ppm 5th 0.060 0.059 0.059 0.061 0.058 0.060 0.061 0.063 0.059 0.060 4th Max. 8-hr. 661 ppm Arith. Mean 0.086 0.085 0.086 0.081 0.082 0.083 0.087 0.083 0.083 0.086 PM10 Annual Avg. 934 mg/m3 95th 51.5 46.4 46.4 42.0 41.5 39.4 38.8 37.6 37.5 35.8 Annual Avg. 934 mg/m3 90th 43.3 39.8 39.9 36.4 35.9 36.4 34.8 33.0 32.4 31.8 Annual Avg. 934 mg/m3 75th 36.3 34.5 33.7 31.0 30.2 30.4 29.1 27.7 27.3 27.7 Annual Avg. 934 mg/m3 50th 30.1 28.2 28.2 25.8 25.4 25.6 24.3 23.2 23.2 23.6 Annual Avg. 934 mg/m3 25th 25.3 23.4 23.6 22.0 21.0 21.1 19.8 19.3 19.4 19.3 Annual Avg. 934 mg/m3 10th 20.1 18.9 18.4 17.6 16.7 16.7 15.5 16.0 15.3 15.2 Annual Avg. 934 mg/m3 5th 17.1 15.7 14.5 13.6 12.7 13.1 12.2 12.2 12.1 12.3 Annual Avg. 934 mg/m3 Arith. Mean 31.7 29.4 29.1 26.8 26.0 26.0 24.9 23.9 23.8 23.7 Sulfur Dioxide Annual Mean 482 ppm 95th 0.0183 0.0175 0.0162 0.0154 0.0153 0.0143 0.0115 0.0113 0.0107 0.0106 Annual Mean 482 ppm 90th 0.0153 0.0146 0.0138 0.0128 0.0126 0.0122 0.0101 0.0097 0.0090 0.0095 Annual Mean 482 ppm 75th 0.0115 0.0107 0.0099 0.0095 0.0092 0.0090 0.0074 0.0074 0.0071 0.0069 Annual Mean 482 ppm 50th 0.0080 0.0077 0.0076 0.0069 0.0067 0.0065 0.0051 0.0053 0.0051 0.0049 Annual Mean 482 ppm 25th 0.0048 0.0044 0.0046 0.0043 0.0040 0.0037 0.0033 0.0032 0.0031 0.0032 Annual Mean 482 ppm 10th 0.0024 0.0022 0.0022 0.0020 0.0022 0.0021 0.0018 0.0018 0.0018 0.0019 Annual Mean 482 ppm 5th 0.0016 0.0015 0.0016 0.0014 0.0015 0.0015 0.0014 0.0014 0.0014 0.0014 Annual Mean 482 ppm Arith. Mean 0.0087 0.0082 0.0079 0.0074 0.0072 0.0069 0.0056 0.0056 0.0054 0.0053 2nd Max. 24-hr. 486 ppm 95th 0.0960 0.0870 0.0750 0.0750 0.0720 0.0720 0.0555 0.0600 0.0520 0.0520 2nd Max. 24-hr. 486 ppm 90th 0.0740 0.0660 0.0610 0.0610 0.0580 0.0620 0.0470 0.0470 0.0450 0.0430 2nd Max. 24-hr. 486 ppm 75th 0.0520 0.0480 0.0440 0.0440 0.0420 0.0440 0.0330 0.0330 0.0330 0.0310 2nd Max. 24-hr. 486 ppm 50th 0.0380 0.0330 0.0320 0.0300 0.0280 0.0320 0.0220 0.0230 0.0230 0.0220 2nd Max. 24-hr. 486 ppm 25th 0.0230 0.0210 0.0200 0.0190 0.0180 0.0190 0.0150 0.0150 0.0140 0.0140 2nd Max. 24-hr. 486 ppm 10th 0.0110 0.0100 0.0100 0.0100 0.0100 0.0090 0.0080 0.0090 0.0070 0.0080 2nd Max. 24-hr. 486 ppm 5th 0.0070 0.0060 0.0070 0.0060 0.0055 0.0050 0.0050 0.0050 0.0050 0.0050 2nd Max. 24-hr. 486 ppm Arith. Mean 0.0414 0.0375 0.0348 0.0339 0.0324 0.0340 0.0257 0.0262 0.0250 0.0240