Influence of wildfire smoke on summertime surface air quality in an urban desert region

The impact of wildfire smoke on surface air quality is examined for one of the largest metro areas in the United States (Phoenix, Arizona) as a case study of urban areas in arid regions. While many studies have examined direct smoke impacts at surface level, the present work seeks to also identify the composite impact of smoke throughout the atmospheric column on surface air quality. O₃ and PM_2.5 concentrations increased on smoke days compared to no smoke days, although increases in these pollutants were not distributed equally across the study region. O₃ and PM_2.5 showed concurrent increases on smoke days, while no relationship between the two was found for no smoke days. Smoke days tended to have higher mean daily air temperatures than no smoke days (34.1 ^°C vs. 32.9 ^°C, respectively). Given that the National Ambient Air Quality Standard (NAAQS) for O₃ was exceeded on 51 % of smoke days compared to 28 % of no smoke days examined, results of this work highlight the need to understand the mechanisms by which wildfire smoke throughout the atmospheric column impacts surface air quality to develop effective strategies for protecting vulnerable populations and improving air quality.