Historic Ozone Air Quality Trends

Year	Old Federal Standard* (1-hour average > 0.12 ppm)	1997 Federal Standard* (8-hour average > 0.08 ppm)	2008 Federal Standard* (8-hour average > 0.075 ppm	Health Advisory (1-hour average ³ 0.15 ppm)	Stage 1 Episode (1-hour average ³ 0.20 ppm)	Basin Maximum 1-hour average (ppm)	Basin Maximum 8-hour Average (ppm)
1976	194	206	213	166	102	0.38	0.268
1977	208	223	232	184	121	0.39	0.284
1978	187	200	219	173	116	0.43	0.321
1979	191	204	234	169	120	0.45	0.312
1980	167	186	210	152	101	0.41	0.288
1981	180	198	227	159	99	0.37	0.266
1982	149	168	194	121	63	0.40	0.266
1983	152	169	191	138	84	0.39	0.245
1984	173	194	213	146	97	0.34	0.249
1985	158	188	210	136	83	0.39	0.288
1986	164	194	220	140	79	0.35	0.251
1987	160	182	200	130	66	0.33	0.210
1988	178	197	217	144	77	0.35	0.258
1989	157	186	220	120	54	0.34	0.253
1990	130	163	191	107	41	0.33	0.194
1991	130	162	186	100	47	0.32	0.204
1992	143	176	201	109	41	0.30	0.219
1993	124	170	193	92	24	0.28	0.195
1994	118	152	174	96	23	0.30	0.209
1995	98	122	151	59	14	0.26	0.204
1996	90	127	154	53	7	0.24	0.175
1997	68	138	174	28	1	0.21	0.165
1998	62	119	147	43	12	0.24	0.206
1999	41	120	152	12	0	0.17	0.143
2000	40	106	137	17	0	0.184	0.159
2001	36	93	132	15	0	0.190	0.146
2002	49	99	135	18	0	0.167	0.148
2003	68	120	141	36	1	0.216	0.200
2004	28	90	126	4	0	0.163	0.148
2005	30	84	117	11	0	0.182	0.145
2006	35	86	116	10	0	0.175	0.142
2007	18	79	108	5	0	0.171	0.137
2008	28	80	120	7	0	0.176	0.131

ppm = parts per million parts of air, by volume.
* The federal 8-hour ozone standard was revised from 0.08 ppm to 0.075 ppm, effective May 27, 2008.
a) Basin-days represents the number of days a standard was exceeded anywhere in the South Coast Air Basin.

Historic Ozone Air Quality Trends

Year

Health Advisory (1-hour average ³ 0.15 ppm)

Stage 1 Episode (1-hour average ³ 0.20 ppm)

Basin Maximum 1-hour average (ppm)

Basin Maximum 8-hour Average (ppm)

Health Advisory
(1-hour average
³ 0.15 ppm)

Stage 1 Episode
(1-hour average
³ 0.20 ppm)

Basin
Maximum
1-hour average
(ppm)

Basin Maximum 8-hour Average
(ppm)