Today's High Ozone Readings

Today's ozone levels again rose to unhealthy levels. Get this. As of 8 P.M., 12 of 15 ozone monitors in the Front Range region (from Fort Collins to Colorado Springs) reported ozone levels above 80 parts per billion, or levels that threatened human health. 7 of 15 monitors registered "technical" exceedances of the EPA's 8-hour ozone ambient air quality standard (which, due to an outdated rounding scheme, is 85 parts per billion).

In terms of the summer's overall ozone data though, today's ozone levels mark a milestone. Whether or not an area is meeting ambient air quality standards for the 8-hour ozone standard is based on whether the three year average of the fourth highest maximum daily value exceeds 85 parts per billion (again, this is the EPA's outdated rounding scheme at play).

Because of today's ozone levels, the fourth highest maximum value has exceed 85 ppb for this year at two additional monitors--Chatfield and Rocky Flats North. Previously, the fourth highest max exceeded 85 ppb at only the Ft. Collins west monitor. The most current data is presented below (red highlight shows a violation of 85 ppb):

Monitor	1st Max.	2nd	3rd	4th
Welby	81	70	69	69
Highland	85	82	82	81
S. Boulder Creek	87	86	86	82
CAMP (Denver)	70	65	63	61
Carriage	92	74	74	72
Chatfield	92	88	86	86
Colorado Springs	73	73	72	71
Manitou Springs	79	78	77	76
Arvada	83	83	82	81
Welch	96	87	82	81
Rocky Flats North	94	93	91	90
NREL (Golden)	94	89	84	83
Ft. Collins West	97	95	88	87
Ft. Collins	82	80	79	78
Greeley	90	87	84	82