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Virginia Administrative Code
Title 9. Environment
Agency 5. State Air Pollution Control Board
Chapter 60. Hazardous Air Pollutant Sources
11/23/2024

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.

Statutory Authority

§ 10.1-1308 of the Code of Virginia; §§ 110, 111, 123, 129, 171, 172, and 182 of the Clean Air Act; 40 CFR Parts 51 and 60.

Historical Notes

Derived from VR120-06-0101, eff. April 1, 1988; amended, Virginia Register Volume 12, Issue 3, eff. December 1, 1995; Volume 13, Issue 14, eff. May 1, 1997; Volume 14, Issue 11, eff. April 1, 1998; Volume 15, Issue 13, eff. April 14, 1999; Virginia Register Volume 16, Issue 14, eff. May 1, 2000; Volume 17, Issue 15, eff. June 1, 2001; Volume 18, Issue 7, eff. February 1, 2002; Volume 19, Issue 6, eff. February 1, 2003; Volume 20, Issue 16, eff. June 1, 2004; Volume 21, Issue 7, eff. January 12, 2005; Volume 22, Issue 4, eff. December 1, 2005; Volume 23, Issue 17, eff. June 1, 2007; Volume 24, Issue 5, eff. December 12, 2007; Volume 25, Issue 12, eff. March 18, 2009; Volume 26, Issue 8, eff. January 20, 2010; Volume 27, Issue 11, eff. March 2, 2011; Volume 28, Issue 10, eff. February 15, 2012; Volume 29, Issue 10, eff. February 13, 2013; Volume 30, Issue 10, eff. July 1, 2014; Volume 31, Issue 12, eff. March 11, 2015; Volume 32, Issue 10, eff. February 10, 2016; Volume 33, Issue 10, eff. February 22, 2017; Volume 34, Issue 11, eff. February 21, 2018; Volume 35, Issue 11, eff. February 20, 2019; Volume 36, Issue 12, eff. March 4, 2020; Volume 37, Issue 4, eff. November 11, 2020.

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