Technology Transfer Network / NAAQS
Table 4. Areas not meeting the 8-hour Carbon Monoxide National Ambient Air Quality Standard, 1997-98
1. The level of the 8-hour National Ambient Air Quality Standard for carbon monoxide is 9 parts per million (ppm) not to be exceeded more than once per year. The design value for the 8-hour CO NAAQS is the highest annual second maximum nonoverlapping 8-hour concentration during the most recent two years.
2. Annual second highest nonoverlapping 8-hour average CO concentration.
3. Number of nonoverlapping exceedances of the 8-hour CO NAAQS.
SOURCE: U.S. EPA's Aerometric Information Retrieval System (AIRS)