Table 21

Ambient Air Quality Data for the Imperial Valley-Mexicali Area
Ref Pollutant Name Units Yr No. of Arith Std. Geom. Std. High 2nd Hi Highest
# Obs. Mean Dev. Mean Dev. Read. Read. 95%
IV-3 PM-10 ug/m3 91 54 63.1 33.3 56.6 1.61 229 137 134
IV-3 PM-10 ug/m3 92 60 47.3 18.9 43.7 1.51 103 88 80
IV-3 PM-10 ug/m3 93 61 52.4 27.8 47.2 1.58 175 162 98
IV-3 PM-10 ug/m3 94 57 51 24.5 46.5 1.53 126 126 123
IV-3 PM-10 ug/m3 95 59 45.4 21.3 40.8 1.61 122 89 83
IV-3 PM-10 ug/m3 96 41 48.7 37.6 42 1.65 257 100 71
IV-4 Carbon ppm 94 4710 1.14 2.09 0.58 2.73 30.6 25.7 4.6
IV-4 Carbon ppm 95 8289 1.22 2.32 0.59 2.83 32 29.8 4.9
IV-4 Carbon ppm 96 6003 0.89 1.53 0.49 2.53 19.6 19 3.6
IV-4 Lead ug/m3 94 13 0.046 0.055 0.03 2.41 0.21 0.08 0.21
IV-4 Lead ug/m3 95 52 0.026 0.023 0.018 2.36 0.11 0.09 0.09
IV-4 Lead ug/m3 95 15 0.0293 0.0195 0.0227 2.22 0.075 0.05 0.075
IV-4 Lead ug/m3 96 28 0.025 0.02 0.019 2.19 0.07 0.07 0.07
IV-4 Lead ug/m3 96 19 0.0225 0.0178 0.016 2.63 0.08 0.042 0.08
IV-4 Nitrog ppm 94 4770 0.0149 0.0161 0.009 2.73 0.227 0.151 0.048
IV-4 Nitrog ppm 95 8334 0.0158 0.018 0.0054 8.26 0.217 0.186 0.051
IV-4 Nitrog ppm 96 6241 0.012 0.0154 0.0025 12.57 0.164 0.135 0.045
IV-4 Ozone ppm 94 4795 0.0574 0.0231 0.0529 1.51 0.125 0.12 0.106
IV-4 Ozone ppm 95 8339 0.0616 0.0263 0.0572 1.46 0.232 0.205 0.112
IV-4 Ozone ppm 96 6279 0.0664 0.0244 0.0623 1.43 0.159 0.146 0.112
IV-4 PM-10 ug/m3 94 15 115.7 50.4 106.8 1.51 258 153 258
IV-4 PM-10 ug/m3 95 56 65 35.4 55.7 1.79 180 149 142
IV-4 PM-10 ug/m3 96 31 42.8 18.5 39.1 1.55 83 80 80
IV-4 PM-10 ug/m3 96 41 61.3 33.3 52.9 1.76 159 143 130
IV-4 Sulfur ppm 94 4052 0.0066 0.0053 0.0036 4.49 0.06 0.041 0.016
IV-4 Sulfur ppm 95 4787 0.0052 0.005 0.0013 14.58 0.039 0.034 0.015
IV-4 Sulfur ppm 96 5776 0.0029 0.0032 0.0012 7.46 0.036 0.032 0.009
IV-5 Ozone ppm 91 1909 0.0527 0.0293 0.0473 1.56 0.18 0.17 0.12
IV-5 Ozone ppm 92 7810 0.0671 0.0238 0.0632 1.42 0.15 0.15 0.12
IV-5 Ozone ppm 93 7580 0.0696 0.0268 0.0628 1.76 0.21 0.15 0.12
IV-5 Ozone ppm 94 6551 0.0776 0.0219 0.0747 1.32 0.18 0.15 0.12
IV-5 Ozone ppm 95 6146 0.0651 0.028 0.0593 1.56 0.19 0.18 0.11
IV-5 PM-10 ug/m3 94 45 76.1 40.6 65.4 1.81 182 165 159
IV-5 PM-10 ug/m3 95 58 71.6 43.4 59.6 1.88 229 173 152
IV-5 PM-10 ug/m3 95 62 58 38.2 47.2 1.93 195 154 134
IV-5 PM-10 ug/m3 96 3 66 34.7 58.4 1.91 96 74 96
IV-5 PM-10 ug/m3 96 41 67.1 36.6 58.2 1.73 174 166 125
IV-6 Ozone ppm 91 7619 0.0496 0.0192 0.0458 1.51 0.11 0.1 0.09
IV-6 Ozone ppm 92 7966 0.0526 0.0217 0.0479 1.56 0.12 0.11 0.09
IV-6 Ozone ppm 93 8527 0.0629 0.0203 0.0596 1.39 0.15 0.14 0.1
IV-6 Ozone ppm 94 8384 0.062 0.0221 0.0579 1.46 0.13 0.12 0.1
IV-6 Ozone ppm 95 7709 0.0601 0.0245 0.0555 1.51 0.15 0.14 0.11
IV-6 PM-10 ug/m3 91 62 56.6 32.1 50.3 1.63 243 112 97
IV-6 PM-10 ug/m3 92 46 41.4 14.7 38.5 1.5 80 69 60
IV-6 PM-10 ug/m3 93 59 46.5 25.2 41.3 1.63 166 119 92
IV-6 PM-10 ug/m3 94 57 45.3 21.4 40.3 1.67 119 105 86
IV-6 PM-10 ug/m3 95 54 31.2 18 26 1.91 78 76 71
IV-6 PM-10 ug/m3 95 60 41.5 21.6 36.7 1.66 130 92 75
IV-6 PM-10 ug/m3 96 41 49.2 54.6 38.1 1.9 359 110 98
IV-7 PM-10 ug/m3 94 25 43.2 21 39.5 1.52 120 73 73
IV-7 PM-10 ug/m3 95 60 38.8 19.1 34.5 1.65 107 79 72
IV-7 PM-10 ug/m3 96 40 49.1 34.8 42.1 1.7 229 90 88
IV-8 PM-10 ug/m3 94 28 60.5 27.6 54.5 1.6 126 103 103
IV-8 PM-10 ug/m3 95 58 63 29 57 1.58 168 133 122
IV-8 PM-10 ug/m3 96 37 77.5 47.4 68.4 1.6 280 192 192
IV-9 PM-10 ug/m3 91 13 48.8 55.1 37.4 1.88 229 56 229
IV-9 PM-10 ug/m3 92 13 28.5 16.2 24.1 1.87 60 50 60
IV-9 PM-10 ug/m3 93 13 25.2 9.2 23.5 1.5 37 36 37
IV-9 PM-10 ug/m3 96 11 73 70.3 59.2 1.78 282 72 282
Source: US-Mexico Center on Air Pollution
County IV = Imperial Valley
Ref. # Refers to Air Monitor; see Table 18 for monitor numbers and locations
Pollutant Pollutant measured
Unit ppm = parts per million; ug/m3 = micrograms per cubic meter of air;
Year Calendar year
No. of Obs. Number of measurements taken at each monitor
Arith. mean Arithmetic mean for hourly (daily for PM10 and Pb) of each pollutant measured
Std. Dev. Standard deviation of arithmetic mean
Geo. mean Geometric mean for hourly (daily for PM10 and Pb) of each pollutant measured
Std. Dev. Standard deviation of geometric mean
High Read. Highest pollutant hourly/daily readings
2nd. H. Read Second highest pollutant hourly/daily readings
Highest 95% pollutant concentration that 95% of the hourly/daily readings are equal to or less than.