UC Davis

Farmworkers are vulnerable to ambient environmental conditions, and an emerging health hazard is smoke from wildfires and agricultural burning. This smoke poses an immediate threat to the health and wellbeing of farmworkers by increasing the risk of injuries. Additionally, smoke can influence farmers' and farmworkers' decisions about when, where, and how much to work, potentially exacerbating ongoing labor shortages in the agricultural sector. My dissertation quantifies the effect of smoke from 1) wildfires and 2) agricultural burning on farmworker labor and health outcomes.

In the first chapter, we study the effect of wildfire smoke on farmworker labor outcomes in California. Using high-frequency individual-location data, we find that labor declines at both the extensive and intensive margins on days when fields are affected by wildfire smoke. On smoky days, the number of workers in a field is reduced by 17.51% and working hours are reduced by 23.12%, relative to days without smoke. Estimated effects are largest for labor-intensive crops. Farmworkers are more likely to be observed in a field immediately before smoke events and less likely to be observed after. They are also more likely to work in other fields when their primary worksite is treated. Results highlight the significant effects of wildfire smoke on farmworker labor outcomes, showing reductions in work activities and the adoption of substitution behaviors among a marginalized and hard-to-survey group.

In the second chapter, we study the impact of wildfire smoke on workplace injuries among agricultural workers, using workers'-compensation claims between 2007 and 2021. We find a substantial increase in agricultural-worker injuries attributable to wildfire smoke and smoke-induced PM2.5. Specifically, 10 micrograms per cubic meter increase in daily PM2.5 exposure from wildfire smoke increases traumatic injuries by 2.3 percent, and exposure to high levels of PM2.5 (above 20 micrograms per cubic meter) increases traumatic injuries by 14.29 percent relative to days without smoke. The effects of smoke are higher for young workers than for old workers. We find that injuries occur even at levels of PM2.5 considered safe. Our back-of-the-envelope calculation suggests that in 2020 alone, wildfire smoke was responsible for approximately 282 additional agricultural-worker injuries in California compared to a hypothetical scenario without smoke.

In the third chapter, using data from the major seven air districts in California engaged in agricultural burning and worker's compensation claims from 2000 to 2021, we investigate the impact of exposure to smoke from agricultural burning on agricultural workers' injuries. Agricultural burning has long been used for various purposes in U.S. agriculture, such as removing crop residue and controlling pests, resulting in significant emissions of air pollutants. Prior research has mainly focused on its effect on the general population particularly in developing countries. By leveraging daily changes in fire location and wind direction for identification, our findings show that on days with agricultural burnings, there is a 2.6 percent increase in injuries within the downwind zip code. The impact on farmworker injuries is larger when agricultural burnings occur over consecutive days.