Exposure to Wildfire Smoke and Particulate Matter among Washington State Construction Workers; Potential Impacts and Implications for Worker Protection

Driven by climate change, wildfires are increasing in frequency, duration, and intensity across the Western United States. Outdoor workers are being exposed to increasing wildfire-related particulate matter and smoke. Recognizing this emerging risk, Washington adopted an emergency rule and is presently engaged in creating a permanent rule to protect outdoor workers from wildfire smoke exposure. While there are growing bodies of literature on the exposure to and health effects of wildfire smoke in the general public and wildland firefighters, there is a gap in knowledge about wildfire smoke exposure among outdoor workers generally, and construction workers specifically, a large category of outdoor workers in Washington totaling 200,000 people. In this study, we link several data sources including state-collected employment data and national ambient air quality data to gain insight into the risk of wildfire exposure among construction workers in Washington. Our results indicate the number of poor air quality days has increased in August and September in recent years. We also observed that over the last decade these months with the greatest potential for wildfire smoke exposure coincide with an annual peak in construction employment that was typically 9.4 to 42.7% larger across Washington counties (one county was 75.8%). Lastly, we considered different air quality thresholds and retrospectively tallied days in Washington that would have triggered rules protecting workers from wildfire smoke. We found the "encouraged" threshold of the Washington emergency rule (20.5 μg/m3) would result in 5.5 times more days subject to the wildfire rule on average across all Washington counties compared to its "required" threshold (55.5 μg/m3), and in 2020 the rule could have created demand for 1.35 million N-95 filtering facepiece respirators among construction workers. These results have important implications for both employers and policy makers as rules are developed. We also discuss the potential economic and policy implications of wildfire smoke exposure, exposure control strategies, and data gaps that would improve our understanding of construction worker exposure to wildfire smoke.