Spatial patterns in summertime surface ozone in the Southern Front Range of the U.S. Rocky Mountains

Summertime ozone in the Western United States presents a unique public health challenge. Changes population, background ozone, wildland fire, and local precursor emissions combined with terrain-induced meteorology can affect surface levels compliance National Ambient Air Quality Standards (NAAQS). While there is considerable research on Northern Front Range Metropolitan Area of Colorado, States, less known about Southern Range. In Colorado Springs, approximately 100 km south Denver, summertime maximum daily 8-h average (MDA8) shows no significant (p < .05) trend at 5th, 50th, or 95th percentile over past 20 years. However, region risk nonattainment NAAQS based observations from 2018 to 2020. From June through September 2018, Department Public Health Environment measured hourly eight sites characterize spatial distribution Springs. Mean (±1σ) ranged 34 ± 19 60 9 ppb. The increased 1.1 ppb per m elevation, while amplitudes mean diurnal profiles decreased elevation distance interstate. MDA8 was also highly correlated across all sites, little evidence photochemical production transport Denver. Further, results generalized additive modeling show that this strongly influenced by regional air wildfire, smoke contributing an 4–5 MDA8. Enhanced values due wildfires were especially pronounced Lastly, we find permanent monitoring represent lower end observed region, suggesting additional long-term for may be warranted populated, higher areas.