NAC445B.22097. Standards of quality for ambient air.

     1. The table contained in this section lists the minimum standards of quality for ambient air.

		NEVADA STANDARDSA			NATIONAL STANDARDSB
POLLUTANT	AVERAGING TIME	CONCENTRATIONC	METHODD		PRIMARYC, E	SECONDARYC, F	METHODD
Ozone	8 hours	0.075 ppm	Chemiluminescence		0.075 ppm	Same as primary	Chemiluminescence
Ozone-Lake Tahoe Basin, #90	1 hour	0.10 ppm (195 µg/m3)	Ultraviolet absorption		--	--	--
Carbon monoxide less than 5,000′ above mean sea level	8 hours	9 ppm (10,500 µg/m3)	Nondispersive infrared photometry		9 ppm (10 mg/m3)	None	Nondispersive infrared photometry
At or greater than 5,000′ above mean sea level		6 ppm (7,000 µg/m3)
Carbon monoxide at any elevation	1 hour	35 ppm (40,500 µg/m3)			35 ppm (40 mg/m3)
Nitrogen dioxide	Annual arithmetic mean	0.053 ppm (100 µg/m3)	Gas phase chemiluminescence		53 ppbG	Same as primary	Gas phase chemiluminescence
	1 hour	--	--		100 ppb	None
Sulfur dioxide	Annual arithmetic mean	0.030 ppm (80 µg/m3)	Ultraviolet fluorescence		0.03 ppmH (1971 standard)	None	Spectrophotometry (Pararosaniline method)
	24 hours	0.14 ppm (365 µg/m3)			0.14 ppmH (1971 standard)
	3 hours	0.5 ppm (1,300 µg/m3)			None	0.5 ppm
	1 hour	--	--		75 ppb	None
Particulate matter as PM10	Annual arithmetic mean	50 µg/m3	High volume PM10 sampling		None	None	--
	24 hours	150 µg/m3			150 µg/m3	Same as primary	High or low volume PM10 sampling
Particulate matter as PM2.5	Annual arithmetic mean	--	--	15.0 µg/m3		Same as primary	Low volume PM2.5 sampling
	24 hours	--	--	35 µg/m3		Same as primary
Lead (Pb)	Rolling 3 mo. average	0.15 µg/m3	High volume sampling, acid extraction and atomic absorption spectrometry		0.15 µg/m3	Same as primary	High volume sampling, acid extraction and atomic absorption spectrometry
Hydrogen sulfide	1 hour	0.08 ppm (112 µg/m3)I	Ultraviolet fluorescence		--	--	--

Notes:

Note A: The Director shall use the Nevada standards in considering whether to issue a permit for a stationary source and shall ensure that the stationary source will not cause the Nevada standards to be exceeded in areas where the general public has access.

Note B: The National standards are used in determinations of attainment or nonattainment. The form of a National standard is the criteria which must be satisfied for each respective concentration level of a standard for the purposes of attainment. The form for each National standard is set forth in 40 C.F.R. Part 50 and may be viewed at http://www.epa.gov/air/criteria.html.

Note C: Where applicable and except as otherwise described in Note G, concentration is expressed first in units in which it was adopted. All measurements of air quality that are expressed as mass per unit volume, such as micrograms per cubic meter, must be corrected to a reference temperature of 25 degrees Centigrade and a reference pressure of 760 mm of Hg (1,013.2 millibars); “ppb” in this table refers to parts per billion by volume, or nanomoles of regulated air pollutant per mole of gas; “ppm” refers to parts per million by volume, or micromoles of regulated air pollutant per mole of gas; “µg/m³” refers to micrograms per cubic meter.

Note D: Reference method as described by the EPA. Any reference method specified in accordance with 40 C.F.R. Part 50 or any reference method or equivalent method designated in accordance with 40 C.F.R. Part 53 may be substituted.

Note E: National primary standards are the levels of air quality necessary, with an adequate margin of safety, to protect the public health.

Note F: National secondary standards are the levels of air quality necessary to protect the public welfare from any known or anticipated adverse effects of a regulated air pollutant.

Note G: The official National annual standard for nitrogen dioxide is 0.053 ppm. The National annual standard is identified in this table in equivalent units of parts per billion for the purpose of simplifying its comparison with the National 1-hour standard which is also identified in parts per billion.

Note H: The 1971 National sulfur dioxide standards remain in effect for an area until 1 year after the area is designated for the 2010 National sulfur dioxide standard, except that in an area designated nonattainment for the 1971 National sulfur dioxide standards, the 1971 standards remain in effect until an implementation plan to attain or maintain the 2010 National sulfur dioxide standards is approved.

Note I: The ambient air quality standard for hydrogen sulfide does not include naturally occurring background concentrations.

     2. These standards of quality for ambient air are minimum goals, and it is the intent of the Commission in this section to protect the existing quality of Nevada’s air to the extent that it is economically and technically feasible.

     [Environmental Comm’n, Air Quality Reg. §§ 12.1-12.1.6, eff. 11-7-75; A and renumbered as § 12.1, 12-4-76; A 12-15-77; 8-28-79; §§ 12.2-12.4, eff. 11-7-75; § 12.5, eff. 12-4-76; A 8-28-79]—(NAC A 10-19-83; 9-5-84; 12-26-91; 10-30-95; R103-02, 12-17-2002; R198-03, 4-26-2004; R038-12, 9-14-2012; R042-13, 12-23-2013)