Historical Exceedance Days in New England

The chart below shows the number of days air quality monitors in each New England state recorded ozone concentrations exceeding the 2008 8-hour ozone standard (that is, days greater than 0.075 parts per million (ppm)), as well as the number of days exceeding the 2015 8-hour ozone standard (that is, days greater than 0.070 ppm).

Graph Data
Exceedance Days Per Area
Year Pollutant New England
# days >		 Connecticut
# days >		 Maine
# days >		 Massachusetts
# days >		 New Hampshire
# days >		 Rhode Island
# days >		 Vermont
# days >
0.075 0.070 0.075 0.070 0.075 0.070 0.075 0.070 0.075 0.070 0.075 0.070 0.075 0.070
2024* Ozone (O3) 15 24 14 23 1 2 1 5 0 1 2 3 0 0
2023 Ozone (O3) 12 21 11 20 0 0 6 10 2 4 5 7 0 2
2022 Ozone (O3) 14 24 12 23 1 2 1 4 1 2 3 5 0 0
2021 Ozone (O3) 18 23 16 21 3 4 2 4 2 3 2 5 0 0
2020 Ozone (O3) 9 18 9 17 0 1 1 3 0 0 2 4 0 0
2019 Ozone (O3) 14 24 12 21 0 1 2 5 0 1 1 2 0 0
2018 Ozone (O3) 18 28 17 23 2 3 6 12 1 6 5 12 0 1
2017 Ozone (O3) 17 25 10 20 5 6 6 12 3 5 5 6 0 1
2016 Ozone (O3) 21 32 21 31 1 4 7 11 0 5 4 6 0 1
2015 Ozone (O3) 24 38 22 33 2 4 3 15 3 7 4 10 0 0
2014 Ozone (O3) 9 20 8 16 0 3 0 4 1 4 0 2 0 0
2013 Ozone (O3) 20 27 18 23 5 8 6 13 3 6 7 11 0 1
2012 Ozone (O3) 29 39 37 36 4 5 17 27 3 12 11 17 0 1
2011 Ozone (O3) 16 24 14 20 3 7 10 15 2 4 6 11 1 1
2010 Ozone (O3) 29 45 24 37 8 9 14 23 8 11 6 11 0 3
2009 Ozone (O3) 11 19 6 18 3 5 8 11 2 5 1 6 0 3
2008 Ozone (O3) 39 45 22 32 4 10 18 29 10 20 6 13 3 4
2007 Ozone (O3) 53 62 42 54 14 17 38 48 22 24 18 28 5 7
2006 Ozone (O3) 37 45 29 34 10 16 26 34 11 18 13 19 0 3
2005 Ozone (O3) 43 57 30 41 15 22 31 47 17 26 17 23 4 10
2004 Ozone (O3) 28 38 20 26 11 17 16 29 10 15 5 12 4 5
2003 Ozone (O3) 34 51 26 37 15 19 27 38 10 21 13 18 4 7
2002 Ozone (O3) 53 60 49 55 28 29 43 56 23 30 33 37 13 19
2001 Ozone (O3) 47 59 39 41 22 30 37 48 22 31 26 33 9 16
2000 Ozone (O3) 27 39 23 31 5 14 16 25 5 6 14 17 2 6
1999 Ozone (O3) 50 62 43 54 21 27 36 47 19 29 16 22 11 18
1998 Ozone (O3) 52 69 44 53 22 36 36 51 14 19 11 18 5 11
1997 Ozone (O3) 47 58 34 44 16 25 38 48 16 23 19 19 11 9
1996 Ozone (O3) 44 56 33 39 20 29 28 38 14 21 12 14 4 10
1995 Ozone (O3) 48 60 35 44 23 32 33 48 19 27 18 22 13 13
1994 Ozone (O3) 53 70 39 57 22 27 39 49 21 33 21 28 13 11
1993 Ozone (O3) 51 60 39 49 20 26 40 51 18 25 11 14 9 13
1992 Ozone (O3) 47 62 29 38 22 27 36 49 16 20 12 20 11 13
1991 Ozone (O3) 54 69 46 57 26 33 45 52 22 25 28 31 16 21
1990 Ozone (O3) 57 68 44 56 21 29 37 50 20 28 18 24 8 17
1989 Ozone (O3) 62 77 41 55 29 27 43 44 14 23 14 22 5 9
1988 Ozone (O3) 72 79 62 70 40 46 63 65 37 42 29 40 26 35
1987 Ozone (O3) 58 74 44 57 20 27 35 46 29 34 27 34 11 16
1986 Ozone (O3) 53 67 41 57 17 19 32 43 16 16 22 29 6 10
1985 Ozone (O3) 70 85 58 72 35 47 53 68 15 21 27 38 9 14
1984 Ozone (O3) 79 88 63 70 34 42 65 72 19 25 42 51 10 14
1983 Ozone (O3) 113 118 103 111 36 43 84 95 19 29 34 40 7 12

*2024 data preliminary and subject to change.

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Last updated on October 2, 2024