Table 1.
Monthly average of NO2 concentrations (ppb) by state in the month of April of the years 2015–2020 from the AQS sites. The last column shows the percent change in 2020 with respect to the 2015–2019 mean
| State | No. sites | 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | |
|---|---|---|---|---|---|---|---|---|
| Arizona | 4 | 12.49 | 11.68 | 13.58 | 12.82 | 10.33 | 9.06 | − 25.6% |
| California | 56 | 9.73 | 9.23 | 8.79 | 8.85 | 8.13 | 5.92 | − 33.8% |
| Colorado | 7 | 11.37 | 9.87 | 9.39 | 9.94 | 9.5 | 8.25 | − 17.6% |
| Connecticut | 3 | 11.71 | 11.13 | 11.72 | 10.34 | 8.43 | 6.54 | − 38.7% |
| District of Columbia | 1 | 9.19 | 8.74 | 7.43 | 8.25 | 8.46 | 7.26 | − 13.7% |
| Florida | 7 | 5.65 | 4.23 | 4.73 | 5.55 | 5.34 | 4.77 | − 6.5% |
| Georgia | 2 | 11.39 | 12.15 | 10.83 | 11.62 | 10.8 | 10.83 | − 4.7% |
| Hawaii | 1 | 3.04 | 2.99 | 4.59 | 3.21 | 3.72 | 2.85 | − 18.8% |
| Indiana | 4 | 11.49 | 9.43 | 8.32 | 9.89 | 8.2 | 7.2 | − 23.9% |
| Iowa | 1 | 1.42 | 2.33 | 1.66 | 2.08 | 1.9 | 1.69 | − 10.0% |
| Kansas | 4 | 6.10 | 4.86 | 4.4 | 5.98 | 5.16 | 4.47 | − 15.6% |
| Kentucky | 1 | 13.94 | 14.95 | 13.08 | 13.18 | 17.43 | 11.25 | − 22.5% |
| Maine | 2 | 4.30 | 3.67 | 3.99 | 4.03 | 3.39 | 2.83 | − 27.0% |
| Maryland | 5 | 10.43 | 10 | 8.57 | 8.84 | 8.11 | 6.74 | − 26.7% |
| Massachusetts | 8 | 9.47 | 9.08 | 7.15 | 8.45 | 6.47 | 5.15 | − 36.6% |
| Michigan | 2 | 9.37 | 8.28 | 8.37 | 8.59 | 7.39 | 6.79 | − 19.2% |
| Minnesota | 2 | 7.51 | 5.95 | 7.25 | 9.88 | 6.53 | 5.08 | − 31.6% |
| Mississippi | 1 | 3.91 | 4.25 | 4.28 | 3.85 | 3.79 | 2.68 | − 33.3% |
| Missouri | 6 | 10.81 | 9.17 | 8.82 | 8.62 | 8.64 | 6.92 | − 24.9% |
| Montana | 1 | 0.54 | 0.61 | 0.9 | 0.68 | 0.46 | 0.36 | − 43.5% |
| Nevada | 2 | 8.48 | 7.93 | 9.77 | 10.09 | 8.53 | 6.76 | − 24.5% |
| New Jersey | 8 | 13.80 | 13.39 | 12.33 | 12.48 | 12.38 | 8.03 | − 37.6% |
| New Mexico | 8 | 4.68 | 4.56 | 4.48 | 4.74 | 5.22 | 3.58 | − 24.4% |
| New York | 5 | 13.64 | 12.56 | 12.05 | 12.42 | 11.3 | 7.55 | − 39.1% |
| North Carolina | 3 | 6.04 | 6.29 | 6.05 | 6.11 | 6.58 | 4.4 | − 29.1% |
| North Dakota | 6 | 2.91 | 1.98 | 2.44 | 2.59 | 2.16 | 1.95 | − 19.3% |
| Ohio | 5 | 14.60 | 12.13 | 10.84 | 11.17 | 11.28 | 8.25 | − 31.3% |
| Oklahoma | 3 | 8.89 | 8.43 | 7.02 | 7.38 | 7.38 | 6.02 | − 23.0% |
| Oregon | 2 | 12.39 | 11.59 | 10.69 | 9.42 | 9.98 | 7.77 | − 28.2% |
| Pennsylvania | 1 | 12.87 | 12.89 | 11.74 | 10.81 | 8.7 | 10.39 | − 8.9% |
| Rhode Island | 2 | 14.03 | 13.5 | 10.23 | 13.37 | 10.15 | 8.47 | − 30.9% |
| South Carolina | 2 | 5.59 | 6.03 | 6.73 | 6.62 | 5.84 | 4.92 | − 20.2% |
| Texas | 40 | 5.80 | 6.23 | 5.23 | 6.41 | 5.95 | 5.26 | − 11.2% |
| Utah | 7 | 3.42 | 2.95 | 4.5 | 4.15 | 2.92 | 2.32 | − 35.3% |
| Vermont | 2 | 7.32 | 6.12 | 6.23 | 6.16 | 5.74 | 4.00 | − 36.7% |
| Virginia | 9 | 5.77 | 5.05 | 4.92 | 5.25 | 5.42 | 4.04 | − 23.5% |
| Washington | 2 | 16.80 | 18.17 | 14.25 | 13.32 | 11.36 | 9.52 | − 35.6% |
| Wisconsin | 2 | 12.50 | 11.11 | 9.61 | 11.36 | 9.75 | 8.63 | − 20.6% |
| Wyoming | 13 | 1.69 | 1.62 | 1.61 | 1.55 | 1.31 | 1.33 | − 14.5% |