A new study has taken a closer look at how wildfire smoke affects air quality in Reno, Nevada. Published in the journal Atmospheric Pollution Research, the research compares air quality data from smoke-free days in August–October 2019 with smoke-affected days in the same period in 2020. Scientists measured levels of fine particulate matter (PM 2.5), organic and elemental carbon, ozone, and over 100 toxic compounds called polycyclic aromatic hydrocarbons (PAHs). The findings reveal that all pollutants were higher on smoky days, with PM 2.5 levels surpassing U.S. Environmental Protection Agency (EPA) standards on 18 of 50 days. Ozone levels rose by about 12%, and PAHs were between 6.3 and 47 times higher than on smoke-free days. The study points out that many of these pollutants can pose serious health risks. Earlier research has connected high PM 2.5 levels from wildfires to increased emergency room visits for asthma in Reno and Sparks. The most severe air quality impacts were recorded during August 19–22, 2020, and September 11–17, 2020, when hundreds of wildfires were active in California, sending thick smoke across the region. Wildfire smoke can contribute to the formation of ground-level ozone, a harmful air pollutant, through chemical reactions involving volatile organic compounds (VOCs), free radicals, nitrogen oxides (NOx), and sunlight. However, the study found only a modest 12% increase in ozone on smoky days, with some days showing lower than average ozone levels. This suggests that vehicle emissions and other local sources are the primary contributors to ground-level ozone in the area. The study also looked at PAHs, which are produced during incomplete combustion and can exist in both gas and particulate forms. It found that nearly 98% of the PAHs detected were in the gas phase, with concentrations up to 47 times higher than those in the particulate form. Naphthalene, a gas-phase PAH, is classified as a hazardous air pollutant by the EPA. While the EPA monitors 16 priority PAHs for air quality, only three of those were among the top 20 found in this study. The researchers suggest that current monitoring practices may not fully capture the health risks posed by these pollutants. The study calls for more research on the health effects of these pollutants and for regular monitoring of a broader range of PAHs, especially in areas frequently affected by wildfire smoke. This could help better understand the long-term risks to public health and improve air quality management strategies.