Exposure of agricultural workers in California to wildfire smoke under past and future climate conditions

Abstract

Wildfire activity in the western U.S. has increased in frequency and severity in recent decades. Wildfire smoke emissions contribute to elevated fine particulate matter (PM2.5) concentrations that are dangerous to public health. Due to the outdoor and physically demanding nature of their work, agricultural workers are particularly vulnerable to wildfire smoke pollution. In this study, we quantify the potential exposure of agricultural workers in California to past (2004–2009) and future (2046–2051) smoke PM2.5. We find that while absolute increases in smoke PM2.5 exposure are largest in northern California, agricultural regions in the Central Valley and Central Coast may be highly vulnerable to future increases in smoke PM2.5 concentrations. We find an increase from 6 to 8 million worker smoke exposure days (+35%) of ‘smokewave’ exposure for agricultural workers across the state under future climate conditions, with the largest increases in Tulare, Monterey, and Fresno counties. Under future climate conditions, we find 1.9 million worker smoke exposure days of agricultural worker exposure to levels of total PM2.5 pollution deemed ‘Unhealthy for Sensitive Groups.’ This is a 190% increase over past climate conditions. Wildfire smoke PM2.5 contributes, on average, to more than 90% of these daily PM2.5 exceedances compared with non-fire sources of air pollution. Using the recent extreme wildfire season of 2020 as a case study, we show that existing monitoring networks do not provide adequate sampling of PM2.5 in many future at-risk wildfire regions with large numbers of agricultural workers. Policies will need to consider the changing patterns of smoke PM2.5 exposure under future climate conditions to better protect outdoor agricultural workers.

Evaluation of Model-Based PM2.5 Estimates for Exposure Assessment during Wildfire Smoke Episodes in the Western U.S.

“…Our conclusion that more western wildfire-specific monitoring is needed to capture population exposure to wildfire smoke is in agreement with the findings of two studies published in 2022, which used very different methodologies�one used mode decomposition on the Di estimates 45 and the other used chemical transport modeling under past and future climate conditions. 46 Both of these studies focused on the network of EPA monitors (and our study additionally used the USFS mobile smoke monitors), but another possibility for future years is including data from low-cost air quality sensors, which are much less accurate than EPA monitors and the mobile smoke monitors, but can provide more high-resolution spatial and temporal information on PM 2.5 . 11 During the 2021 fire season, the USFS deployed low-cost sensors to fill a shortage in the smoke monitors.…”

Wildfires and the COVID-19 pandemic: a systematized literature review of converging health crises

“…Farmworkers represent another key occupational group disproportionately exposed not only to wildfire smoke [68] but also to COVID-19 [69]. A study of California farmworkers found that COVID-19 infections were elevated by a factor of four due to essential worker status and socioeconomic vulnerabilities [69].…”

Prescribed Burns as a Tool to Mitigate Future Wildfire Smoke Exposure: Lessons for States and Rural Environmental Justice Communities

“…Such progress in spatial resolution has led to an increased focus on urban centers at the expense of rural communities also vulnerable to pollution, especially from smoke (Pellow, 2016). For example, outside of metropolitan hubs, the Central Valley in California and Central/Eastern Washington State have large populations of non‐white Hispanic agricultural workers who are disproportionately affected by smoke PM 2.5 as an occupational hazard (Cedar River Group, 2012; Chandrasekaran, 2021; Garcia, 2007; Marlier et al., 2022), but whose PM 2.5 exposure is not well monitored (deSouza and Kinney, 2021; Kelp et al., 2022). The Navajo nation, a Native American reservation in the Southwest, is the largest land area held by an indigenous tribe in the United States (Guiterman et al., 2019).…”