unhealthful day

Any day in which the air quality for any of the 5 major ambient air pollutants—carbon monoxide, nitrogen dioxide, ozone, particulate matter, sulphur dioxide—exceeds an established air quality standard

unhealthful day

Public health Any day in which the air quality for any of the 5 ambient air pollutants–carbon monoxide, nitrogen dioxide, ozone, particulate matter, sulfur dioxide exceeds an established air quality standard. See Pollution Standards Index. Cf Unhealthy day.
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References in periodicals archive ?
VENTURA - The first unhealthful day of the 2000 smog season was registered in the Simi Valley and Moorpark areas during the hot weekend, air pollution officials said Monday.
State officials believe the three bills before the state Assembly will in the long term help reduce those unhealthful days.
Health-related air quality was described in terms of the number of good days, moderate days, unhealthful days, very unhealthful days, and hazardous days.
In the South Coast Air Basin, which covers Los Angeles and the San Fernando and Santa Clarita valleys, 68 unhealthful days were recorded as of Dec.
In the South Coast air basin, which includes Los Angeles, there were 49 unhealthful days, up from 36 last year and 40 the year before.