TABLE 2—

Mean PM_2.5 (μg/m³) Concentration: 2007–2011

	States With Comprehensive Smoke-Free Indoor Air Laws			States Without Comprehensive Smoke-Free Indoor Air Laws
Year	IL	IA	MD	TX	WV
2007	13.4	12.1	13.5	10.5	15.1
2008	11.7	10.8	12.2	10.0	12.9
2009	11.3	10.6	10.4	9.3	11.3
2010	12.1	11.4	11.0	9.2	12.5
2011	11.9	10.4	10.7	10.0	11.1

Note. PM = particulate matter. The World Health Organization’s target air quality guideline for PM_2.5 is an annual mean of 10 μg/m³.²²

Source. The US Environmental Protection Agency.²¹