9VAC5-60-230: Significant ambient air concentration guidelines

For the purpose of case-by-case consideration between the board and the owner, significant ambient air concentrations are any of the following:

1. For pollutants with a TLV-C®, any one-hour concentration of a toxic pollutant in excess of 1/40 of the TLV-C®.

2. For pollutants with both a TLV-STEL® and a TLV-TWA®, any one-hour concentration of a toxic pollutant in excess of 1/40 of the TLV-STEL® and any annual concentration of a toxic pollutant in excess of 1/500 of the TLV-TWA®.

3. For pollutants with only a TLV-TWA®, any annual concentration of a toxic pollutant in excess of 1/500 of the TLV-TWA® and any one-hour concentration of a toxic pollutant in excess of 1® of the TLV-TWA®.

4. Any concentration resulting from the emissions of a toxic pollutant from an affected facility which the owner knows, or reasonably should be expected to know, may cause, or contribute to, the endangerment of human health.

5. Any concentration, other than those specified in subdivision 1, 2, 3, or 4 of this section, including those resulting from toxic pollutants not having a TLV®, which the board determines to cause, to have the potential to cause, or to contribute to, the endangerment of human health. This determination shall be made by considering information by recognized authorities on the specific health effects of such toxic pollutants.