2002 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 2002 season daily peak 8-hour-averaged ozone concentrations, colored according to Air Quality Index categories (see explanation of colors), at all Massachusetts state ozone monitors. Values shown are preliminary. Quality assurance checks may, for a small number of values, result in slight changes or invalidation. PPB refers to ozone concentration in parts of ozone per billion parts of air. "M" denotes missing data.

May 2002 Peak 8-HR Ozone Concentration (PPB) at MA Monitors

Date	Adams	Aga- wam	Am- herst	Blue Hill	Chic- opee	Fair- haven	Law- rence	L. Island	Lynn	New- bury	Rox- bury	Stow	Truro	Ware	Wor- cester
5/1	39	41	38	48	39	42	37	42	43	43	29	47	48	43	46
5/2	48	37	39	50	37	51	39	50	44	53	23	39	55	48	44
5/3	22	43	40	47	40	45	39	43	43	42	32	43	48	41	46
5/4	40	53	54	61	52	47	46	50	51	52	39	55	55	56	60
5/5	46	48	61	72	59	60	57	58	53	59	54	65	58	64	70
5/6	55	68	65	75	67	57	68	66	60	68	52	75	62	70	78
5/7	42	54	51	60	55	48	51	55	51	55	42	63	52	57	65
5/8	38	41	43	44	49	39	37	43	39	44	33	41	42	49	48
5/9	35	31	32	39	35	40	28	40	34	43	21	27	43	36	33
5/10	29	61	60	68	63	53	55	55	61	61	46	61	61	60	49
5/11	43	58	49	57	58	55	42	47	48	46	40	50	55	51	40
5/12	45	36	37	62	45	55	42	60	52	55	53	47	63	45	38
5/13	45	41	43	60	49	53	46	59	49	56	43	48	60	47	42
5/14	36	45	38	48	46	51	39	43	44	48	32	43	53	44	37
5/15	27	50	48	48	47	45	39	41	42	42	29	43	45	47	38
5/16	31	63	58	69	60	78	48	60	53	63	46	63	82	60	52
5/17	24	49	45	55	51	61	37	42	48	51	37	47	67	48	41
5/18	31	33	32	42	37	38	30	39	36	41	26	32	40	36	31
5/19	32	43	41	51	46	47	40	43	46	43	40	44	48	42	34
5/20	30	45	41	47	46	45	36	37	39	41	31	43	41	44	33
5/21	19	37	34	40	39	38	29	31	35	34	22	35	37	36	28
5/22	20	50	50	58	54	47	43	48	48	47	40	52	50	51	37
5/23	51	58	56	68	59	56	53	59	57	59	48	64	63	59	52
5/24	31	73	70	88	79	71	65	69	76	75	57	78	84	75	65
5/25	39	48	46	46	51	37	31	36	35	36	32	44	36	46	40
5/26	37	33	31	46	35	37	32	43	39	40	36	44	43	36	30
5/27	46	53	59	59	60	50	42	39	45	39	34	49	52	59	40
5/28	41	28	30	31	31	44	24	35	26	42	15	26	39	46	37
5/29	34	36	39	39	44	36	20	30	28	37	16	29	32	45	32
5/30	48	46	47	38	50	28	43	35	37	42	23	46	24	51	41
5/31	56	42	41	46	45	46	47	39	46	51	38	46	42	51	40

June 2002 Peak 8-HR Ozone Concentration (PPB) at MA Monitors

Date	Adams	Aga- wam	Am- herst	Blue Hill	Chic- opee	Fair- haven	Law- rence	L. Island	Lynn	New- bury	Rox- bury	Stow	Truro	Ware	Wor- cester
6/1	58	59	60	67	62	75	54	56	64	60	47	62	73	61	54
6/2	56	49	47	60	53	50	49	51	60	56	49	51	54	53	45
6/3	37	44	40	49	46	48	40	49	49	46	34	41	46	43	33
6/4	47	47	54	58	59	47	37	47	43	44	45	50	49	M	47
6/5	57	47	45	52	49	52	40	44	43	47	40	52	50	44	43
6/6	44	24	25	36	32	39	26	32	30	36	27	36	36	31	M
6/7	30	33	32	36	39	36	26	34	35	38	15	30	35	M	29
6/8	50	50	50	48	53	40	36	35	37	38	31	51	35	M	38
6/9	58	60	58	71	65	51	50	54	64	58	51	57	54	M	53
610	48	53	42	57	52	44	37	45	45	44	32	43	46	42	36
6/11	71	83	66	81	92	67	51	65	70	41	51	80	71	89	79
6/12	61	23	22	36	30	36	M	35	37	38	27	27	41	M	25
6/13	32	27	31	32	28	35	25	36	32	36	21	30	39	21	20
6/14	31	28	23	39	31	40	29	35	35	38	23	28	44	33	27
6/15	31	28	27	41	33	41	28	37	37	40	25	30	46	34	30
6/16	32	21	19	31	25	49	25	33	32	34	24	23	46	31	23
6/17	34	41	37	54	42	57	35	38	48	44	31	43	52	39	35
6/18	40	45	42	50	48	56	32	34	46	47	26	38	55	46	35
6/19	46	75	52	M	67	67	46	60	61	52	39	48	63	64	52
6/20	71	74	70	M	78	58	57	62	66	68	45	73	58	69	68
6/21	71	90	86	M	97	55	88	89	89	94	69	92	59	95	81
6/22	64	60	41	M	58	65	40	59	60	47	51	50	72	51	52
6/23	61	75	52	M	73	64	67	79	82	62	77	87	71	71	70
6/24	44	59	40	M	56	56	39	47	54	42	41	52	53	50	46
6/25	64	71	66	M	71	57	57	62	55	59	43	61	57	67	51
6/26	72	74	67	M	88	68	80	97	109	91	71	96	80	85	83
6/27	53	61	55	82	68	67	57	72	76	64	M	66	75	63	61
6/28	45	43	37	58	49	61	37	M	54	55	M	41	63	41	M
6/29	39	47	34	51	41	40	39	M	42	40	M	46	32	42	M
6/30	51	72	60	68	74	45	51	M	61	59	M	64	38	M	M

July 2002 Peak 8-HR Ozone Concentration (PPB) at MA Monitors

Date	Adams	Aga- wam	Am- herst	Blue Hill	Chic- opee	Fair- haven	Law- rence	L. Island	Lynn	New- bury	Rox- bury	Stow	Truro	Ware	Wor- cester
7/1	67	58	67	83	69	87	56	74	74	66	41	64	81	64	59
7/2	68	54	63	81	67	105	55	69	78	73	45	57	99	62	56
7/3	59	50	49	79	63	86	60	102	98	81	M	49	93	56	M
7/4	51	46	47	58	53	81	46	63	58	53	40	44	86	44	M
7/5	34	41	32	42	41	41	32	36	43	38	30	39	41	38	32
7/6	39	40	36	44	44	47	30	33	42	37	30	34	45	38	31
7/7	44	36	34	33	41	30	23	23	34	35	22	30	32	38	29
7/8	60	56	55	88	58	77	45	74	83	56	71	69	78	56	57
7/9	72	73	55	103	83	72	59	86	100	80	69	81	74	77	74
7/10	31	35	32	42	36	45	24	36	32	38	28	31	40	36	29
7/11	31	33	30	38	34	21	22	34	38	34	26	30	35	33	27
7/12	43	45	46	62	51	53	44	53	54	55	41	46	54	59	43
7/13	75	81	66	79	83	57	59	81	71	66	78	61	61	79	71
7/14	70	75	73	89	80	47	79	79	86	88	74	82	42	77	71
7/15	51	50	53	81	59	66	55	64	75	74	53	62	54	57	69
7/16	31	37	33	M	36	45	24	40	38	37	32	31	42	34	38
7/17	80	69	55	65	66	51	42	49	47	45	45	65	55	70	76
7/18	78	80	68	83	84	104	57	67	78	64	M	63	105	70	74
7/19	45	61	34	53	68	80	M	36	42	M	27	32	74	54	43
7/20	36	44	33	32	37	30	M	29	31	M	22	34	49	34	40
7/21	51	58	57	52	64	38	38	49	50	M	46	49	33	64	58
7/22	74	97	91	66	108	41	78	64	76	81	56	76	45	M	89
7/23	64	61	55	84	68	56	71	80	83	79	56	75	58	66	94
7/24	19	42	32	28	40	24	20	26	25	27	12	28	27	37	35
7/25	37	48	40	34	52	30	30	M	32	33	27	40	32	47	48
7/26	42	44	40	33	49	30	28	31	31	31	23	29	32	42	42
7/27	47	23	28	31	29	32	28	28	29	32	22	28	33	30	31
7/28	50	19	28	49	32	49	41	40	40	44	38	33	40	34	45
7/29	59	52	49	60	60	64	45	49	57	51	33	48	74	55	55
7/30	50	55	48	64	58	73	47	51	59	51	37	50	88	50	54
7/31	47	47	40	57	47	75	45	60	52	M	33	40	60	40	40

August 2002 Peak 8-HR Ozone Concentration (PPB) at MA Monitors

Date	Adams	Aga- wam	Am- herst	Blue Hill	Chic- opee	Fair- haven	Law- rence	L. Island	Lynn	New- bury	Rox- bury	Stow	Truro	Ware	Wor- cester
8/1	53	65	48	74	61	62	55	56	53	46	33	69	50	59	50
8/2	56	61	48	71	66	43	51	45	42	39	36	61	28	52	56
8/3	50	56	45	86	61	76	53	61	68	61	61	53	70	48	52
8/4	74	84	65	84	92	83	58	77	88	78	60	69	80	77	76
8/5	59	46	49	76	58	80	58	69	72	66	50	62	84	57	68
8/6	22	28	23	31	29	33	27	29	35	29	26	26	43	28	28
8/7	28	30	29	41	33	44	32	35	39	32	30	31	42	31	33
8/8	30	30	28	47	31	52	34	40	41	43	31	31	36	31	32
8/9	46	42	32	53	39	41	39	41	40	38	36	44	39	35	40
8/10	75	71	55	86	62	79	59	74	72	67	62	72	80	63	75
8/11	86	93	78	103	95	52	86	87	97	88	89	87	59	96	91
8/12	91	101	78	116	115	46	109	92	97	103	85	107	72	94	102
8/13	96	112	96	134	108	59	105	126	123	119	99	110	112	107	118
8/14	101	118	107	112	118	61	102	117	122	126	76	106	91	110	M
8/15	78	82	82	63	85	39	74	64	66	80	50	67	39	79	67
8/16	63	72	58	78	74	55	69	78	84	83	63	79	55	70	85
8/17	62	59	49	71	60	82	49	51	63	55	48	M	68	60	71
8/18	60	67	68	93	75	69	84	81	87	83	76	M	64	73	87
8/19	54	54	49	82	61	87	65	58	57	61	39	M	61	58	67
8/20	40	37	35	44	40	42	37	37	38	36	30	M	50	39	40
8/21	51	63	46	50	62	40	42	38	38	37	30	M	30	59	54
8/22	57	49	58	75	64	55	77	74	78	83	66	M	47	65	79
8/23	42	34	37	33	45	33	27	30	30	38	18	M	28	45	41
8/24	33	13	14	29	21	28	23	25	27	26	17	M	24	24	27
8/25	33	37	33	53	40	57	40	49	48	45	41	M	32	37	41
8/26	44	32	32	60	42	61	41	46	36	42	41	41	46	44	52
8/27	30	35	31	38	34	39	39	34	33	38	27	36	42	32	46
8/28	28	30	28	25	33	20	16	23	21	25	13	20	24	30	29
8/29	25	19	19	29	22	20	17	30	25	29	13	17	21	25	27
8/30	33	32	30	24	34	23	32	23	26	36	12	34	25	36	42
8/31	39	31	27	34	31	26	26	35	29	33	23	25	31	30	33

September 2002 Peak 8-HR Ozone Concentration (PPB) at MA Monitors

Date	Adams	Aga- wam	Am- herst	Blue Hill	Chic- opee	Fair- haven	Law- rence	L. Island	Lynn	New- bury	Rox- bury	Stow	Truro	Ware	Wor- cester
9/1	38	25	24	36	35	33	30	35	34	36	30	29	32	35	39
9/2	37	25	M	41	30	37	26	38	36	36	27	20	37	29	30
9/3	53	42	M	30	40	28	24	35	33	38	19	17	36	M	31
9/4	52	51	45	64	54	55	48	60	50	38	35	48	48	43	57
9/5	32	33	29	35	34	34	29	32	35	34	22	25	28	32	37
9/6	42	47	39	58	48	44	43	38	53	47	32	M	33	45	45
9/7	52	49	49	69	54	71	59	58	55	53	M	M	64	60	59
9/8	68	74	70	80	83	55	64	82	83	69	M	63	63	87	81
9/9	77	72	61	107	79	69	86	102	91	89	M	M	80	81	84
9/10	77	78	55	91	83	43	81	94	97	92	M	86	60	91	97
9/11	70	31	27	37	32	35	31	33	38	35	M	32	31	33	36
9/12	M	38	33	39	38	38	33	36	35	37	M	33	37	37	40
9/13	63	55	53	60	52	68	48	55	48	56	37	53	68	56	59
9/14	76	78	79	85	78	49	79	70	59	54	57	82	64	82	87
9/15	34	28	28	43	33	42	39	44	34	42	37	37	40	39	41
9/16	37	15	29	27	32	39	16	27	15	29	9	20	32	24	29
9/17	41	25	37	40	40	39	32	34	22	31	18	37	27	43	39
9/18	40	27	35	39	41	43	38	37	27	36	25	38	33	46	44
9/19	55	28	53	58	52	43	55	59	46	58	42	54	44	57	59
9/20	54	29	51	49	53	43	55	51	41	59	36	51	44	61	57
9/21	42	26	41	47	49	36	49	50	41	53	40	46	37	54	54
9/22	39	19	37	36	39	32	45	38	30	42	32	M	32	40	41
9/23	32	15	33	34	33	23	32	25	23	29	22	23	29	38	34
9/24	41	20	24	24	29	22	14	25	19	25	11	10	24	39	27
9/25	46	20	27	31	M	27	28	32	19	33	15	28	27	43	29
9/26	39	6	15	32	22	30	16	32	19	34	13	14	29	28	M
9/27	27	5	9	39	17	30	27	41	25	44	12	19	33	28	23
9/28	34	22	38	40	42	35	35	37	31	34	32	29	33	41	39
9/29	36	16	26	34	33	32	30	30	23	28	25	33	27	M	32
9/30	46	22	40	39	42	38	34	39	36	40	26	38	37	44	39

2002 Ozone Season Summary

Massachusetts endured a severe ozone season (May through September) in 2002, when ground-level ozone exceeded the national eight-hour health standard at one or more state monitors on 29 days. This is the greatest number since the standard went into effect late in 1997, eclipsing the previous high of 27 days set in 2001. To find a worse year, one must go back to 1988 when, had the current 8-hour standard existed, 43 such days would have occurred.

Ozone, harmful to breathe in high concentrations, forms in abundance when hydrocarbons, the main ingredients in gasoline and solvents, and nitrogen oxides, which are produced when fuels are burned, chemically react on hot, sunny days.

And hot, sunny days abounded during the 2002 summer, when weather systems aligned to produce numerous stretches of heat and southwesterly winds, which channeled pollutants along the Northeast urban corridor into Massachusetts. During one particularly unrelenting hot spell, from August 10-19, Massachusetts monitors recorded unhealthy ozone levels on nine of the 10 days.

The chart below depicts the number of days in recent years when Massachusetts? monitors exceeded the 8-hour and the older, less stringent 1-hour national ozone standards. Because these year-to-year changes are largely due to meteorological variability, long-term trends are difficult to gauge. While the 2002 summer featured many unhealthy air days, it was only two years ago, in 2000, that Massachusetts experienced its cleanest ozone year on record.

Chart showing Trend in Massachusetts ozone exceedance days 1994-2001

Elevated ozone levels were, of course, not confined to Massachusetts but were spread over wide areas of the eastern U.S. See EPA AIRNow for daily local and regional ozone maps.