Characterizing changes in extreme ozone levels under 2050s climate conditions: An extreme-value analysis in California

Climate adjusted projections of the distribution and frequency of poor air quality days for the contiguous United States

“…To generate an annualized expected number of ozone exceedance days, we follow the ozone modeling methodology described in Wilson et al (2022) that uses a point process extreme value model with CMAQ data and climate-projected temperature, relative humidity, and vapor pressure deficit as the meteorological controls on extreme ozone levels. Extreme Value Theory (EVT)is a frequently used technique for modeling ozone levels (Smith, 1989;Thompson, 2001;Rieder et al, 2010;Shen et al, 2016) and allows for estimating both the frequency and intensity of ozone exceedances.…”

“…We present a new modeling framework to compute climate-adjusted estimates of air quality hazards for the contiguous United States (CONUS) at 10 km horizontal resolution. The framework blends results from statistical, machine-learning, and climatechemistry models-including a bias-adjusted version of the EPA Community Multiscale Air Quality Model (CMAQ) time series as described in (Wilson et al, 2022)-for ground-level ozone, anthropogenic fine particulate matter (PM2.5), and wildfire smoke PM2.5 into consistent estimates of days exceeding the "unhealthy for sensitive groups" (orange colored) classification on the EPA Air Quality Index for 2023 and 2053. We find that joint PM2.5 and ozone orange+ days range from 1 day to 41 days across CONUS, with a median value of 2 days, across all years.…”

“…These results are supplemented with EPA air quality monitoring station observations for bias correction and wildfire-specific concentrations from a machine learning model from Childs et al (2022). Ozone results are climate-adjusted using previously published methodology in Wilson et al (2022), and smoke results are climate-adjusted using simulated fires' output from the First Street Foundation Wildfire Model (Kearns et al, 2022). The integrated modeling approach provides a consistent set of projections for the number days for both the current conditions and for projected conditions 30 years into the future reaching an "unhealthy for sensitive groups" (orange colored) or above threshold on the EPA Air Quality Index.…”

Ethnoracial Disparities in Nitrogen Dioxide Pollution in the United States: Comparing Data Sets from Satellites, Models, and Monitors

“…43 Although both the LUR and EQUATES provide modeled surface-level NO 2 concentrations, EQUATES represents a complex, dynamical approach for simulating the physical and chemical processes responsible for ambient NO 2 , such as transport and chemistry. EQUATES is being used increasingly to support a variety of studies aimed at understanding historical air quality trends, 44 characterizing future climatedriven changes in air quality, 45 and calculating exposurerelevant air pollution metrics. 46 We also consider EQUATES as it represents an estimate from the policy-relevant CMAQ model developed by the EPA Office of Research and Development that simulates the processes involved with and outcomes of pollution control strategies.…”

Climate adjusted projections of the distribution and frequency of poor air quality days for the Contiguous United States

“…We present a new modeling framework to compute climateadjusted estimates of air quality hazards for the contiguous United States (CONUS) at 10 kilometer horizontal resolution. The framework blends results from statistical, machine-learning, and climatechemistry models -including a bias-adjusted version of the EPA Community Multiscale Air Quality Model (CMAQ) time series as described in (Wilson et al, 2022) -for ground-level ozone, anthropogenic ne particulate matter (PM2.5), and wild re smoke PM2.5 into consistent estimates of days exceeding the 'unhealthy for sensitive groups' (orange colored) classi cation on the EPA Air Quality Index for 2023 and 2053. We nd that joint PM2.5 and ozone orange + days range from 1 day to 41 days across CONUS, with a median value of 2 days, across all years.…”