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2004 Ozone Season Data & Summary
Color-coded review of daily peak 8-hour-averaged ozone concentrations at all Massachusetts state ozone monitors.

This page lists the 2004 season daily peak 8-hour-averaged ozone concentrations at MassDEP monitors across Massachusetts, colored according to health-based Air Quality Index categories (see Ozone Health Guidelines for an explanation of the colors). Values shown are preliminary. Quality assurance checks may, for a small number of values, result in slight changes.

Ozone concentrations are reported in parts per billion (PPB). For example, a concentration of 38 means there was an average of 38 parts of ozone for every billion parts of air on that day at that location. "M" denotes that data is missing for that day at that location because of equipment or network problems, or a newly installed monitor not being operational yet.

May 2004 Peak 8-HR Ozone Concentration (PPB) at MA Monitors
underline

Date Adams Am-
herst		 Blue
Hill		 Chic-
opee		 Fair-
haven		 L.
Island		 Lynn M'thas Vinyrd New-
bury		 Rox-
bury		 Stow Truro Ware

Wor-
cester

5/1 67 59 56 58 48 55 48 51 60 53 57 50 69 63
5/2 33 22 33 25 40 30 25 40 33 27 28 40 32 31
5/3 35 33 37 29 33 29 31 30 30 30 32 36 45 42
5/4 49 27 42 45 43 37 38 45 39 29 38 42 51 46
5/5 47 M 58 26 51 56 45 60 50 46 55 63 50 57

5/6

 54 50 61 51 63 57 47 57 56 45 56 61 63 60
5/7 55 54 65 58 62 58 53 72 57 45 57 74 66 62
5/8 47 43 50 47 49 43 40 48 45 45 46 50 54 51
5/9 58 38 47 39 48 44 41 46 44 46 43 51 49 49
5/10 65 47 46 51 49 44 35 47 45 38 44 54 63 M
5/11 59 54 66 59 82 52 48 71 64 44 56 85 68 65
5/12 70 55 70 62 69 66 52 67 66 44 60 80 72 67
5/13 68 51 51 53 52 44 40 51 47 45 41 61 60 49
5/14 61 40 47 39 45 38 29 43 44 24 45 47 62 57
5/15 54 57 68 78 49 65 53 44 65 59 62 61 82 71
5/16 42 26 28 34 34 20 22 40 25 24 16 41 M 24
5/17 54 45 36 48 35 30 26 33 35 28 35 33 58 45
5/18 52 34 38 38 37 36 30 37 40 31 43 38 49 52
5/19 50 43 46 46 38 44 43 38 49 39 41 44 53 45
5/20 61 48 57 52 49 48 44 48 52 42 54 52 59 57
5/21 51 37 59 47 45 54 48 46 57 40 47 66 55 48
5/22 46 27 46 28 45 43 38 44 47 32 30 43 41 37
5/23 50 27 37 37 43 38 31 46 41 24 24 43 45 41
5/24 51 21 34 20 34 36 35 40 46 27 23 39 29 35
5/25 34 27 42 25 43 42 36 45 45 38 28 46 34 33
5/26 43 24 37 23 42 41 34 44 43 36 28 45 33 33
5/27 55 47 35 48 51 38 32 44 42 28 30 45 57 45
5/28 50 33 34 42 49 32 23 46 37 27 27 45 45 38
5/29 44 38 43 41 45 39 42 43 43 38 37 46 46 41
5/30 44 39 44 44 55 38 40 57 44 37 38 47 49 42
5/31 53 44 52 48 50 48 46 45 51 46 47 54 55 53

June 2004 Peak 8-HR Ozone Concentration (PPB) at MA Monitors
underline

Date Adams Am-
herst		 Blue
Hill		 Chic-
opee		 Fair-
haven

Haver-
hill

 L.
Island		 Lynn M'thas Vinyrd New-
bury		 Rox-
bury		 Stow Truro Ware

Wor-
cester

6/1 53 30 39 35 41 M 40 32 38 42 26 30 37 45 32
6/2 44 32 47 40 58 M 38 36 47 42 30 39 59 44 46
6/3 41 36 35 37 40 M 29 27 34 32 27 32 43 42 37
6/4 41 M 43 42 42 M 33 28 32 38 32 32 33 49 39
6/5 50 22 44 51 47 M 40 38 32 41 37 44 44 56 48

6/6

 44 30 38 34 38 M 36 31 26 39 29 31 41 39 35
6/7 68 47 48 52 50 M 37 30 M 42 26 45 41 67 60
6/8 70 62 100 71 84 M 94 92 M 77 88 85 89 82 82
6/9 68 56 78 62 99 M 67 70 M 66 63 60 107 70 69
6/10 38 21 33 25 38 M 33 33 39 39 22 24 38 45 41
6/11 39 38 44 42 56 M 42 42 55 42 33 33 47 47 39
6/12 44 37 49 42 43 M 37 38 41 40 38 38 39 46 41
6/13 66 61 58 64 41 M 56 64 37 62 61 56 47 70 63
6/14 48 27 35 28 42 M 34 31 39 36 24 34 38 37 38
6/15 64 56 73 60 64 M 58 69 42 58 49 38 75 64 62
6/16 60 47 68 73 52 52 51 57 72 52 45 49 58 61 56
6/17 56 40 95 58 53 46 66 58 M 48 42 56 61 56 57
6/18 49 44 56 53 47 39 52 56 43 50 39 40 56 58 52
6/19 48 39 46 43 50 36 40 46 53 40 34 37 52 46 43
6/20 38 30 34 33 42 28 28 35 46 33 29 28 42 36 32
6/21 63 46 M 50 57 44 52 56 M 49 43 48 59 54 53
6/22 61 24 M 42 47 30 45 48 47 43 35 40 52 45 45
6/23 48 38 M 44 65 44 54 55 74 51 39 40 65 48 46
6/24 81 76 M 80 68 38 55 67 68 50 49 68 74 83 74
6/25 53 47 59 49 43 57 49 59 45 61 41 45 47 52 55
6/26 45 36 46 43 41 24 26 34 44 38 28 32 39 45 45
6/27 41 37 43 41 54 36 36 45 58 40 36 M 53 45 42
6/28  41 33 48 37 61 32 42 45 64 39 37 35 67 41 40
6/29 41 37 49 37 65 40 43 48 64 45 33 41 52 45 45
6/30 48 43 53 47 73 41 46 54 71 61 36 45 69 56 54

July 2004 Peak 8-HR Ozone Concentration (PPB) at MA Monitors
underline

Date Adams Am-
herst		 Blue
Hill		 Chic-
opee		 Fair-
haven		 Haver-hill L.
Island		 Lynn M'thas Vinyrd New-
bury		 Rox-
bury		 Stow Truro Ware

Wor-
cester

7/1 71 46 70 62 64 66 63 64

62

 68 57 63 72 72 67
7/2 58 47 65 54 56 53 42 63 54 63 46 52 57 57 60
7/3 32 28 48 33 58 41 38 40 56 40 34 30 42 35 31
7/4 60 56 62 63 80 47 48 61 78 49 50 39 51 61 48
7/5 45 33 35 36 47 28 32 32 43 35 29 M 42 45 37

7/6

 33 25 36 30 47 34 37 39 49 39 26 M 44 41 32
7/7 53 55 50 68 45 41 35 38 43 40 24 55 33 60 52
7/8 47 40 38 56 52 24 31 33 M 37 31 31 43 60 44
7/9 43 29 43 36 54 36 35 44 55 42 32 32 53 38 36
7/10 31 29 36 35 54 30 31 40 59 38 27 27 45 36 32
7/11 36 28 40 34 39 35 23 33 38 31 26 39 26 46 44
7/12 37 39 23 39 48 39 44 47 34 46 35 46 40 47 46
7/13 41 29 45 35 49 37 45 47 48 52 33 33 51 46 42
7/14 43 29 39 33 45 38 41 44 47 44 26 31 49 46 40
7/15 42 38 64 47 71 32 60 56 68 50 47 55 63 55 56
7/16 35 29 54 37 63 41 53 56 59 52 42 41 60 41 43
7/17 31 29 46 34 69 30 45 55 58 51 37 29 61 42 40
7/18 59 38 64 61 61 58 48 64 53 53 52 61 56 64