Farmworkers are reducing their hours or relocating to avoid wildfire smoke

Millions of cell tower pings due to dating, weather, Messaging and other mobile apps that use location-sharing services are helping agricultural economists better understand how farmworkers respond to environmental threats like wildfire smoke.

During California’s most devastating wildfire season in 2020, the number of farmworkers in one field studied fell by nearly 35% and the number of hours worked at the same location fell by 37% on smoky days when elevated levels of particulate matter were in the air.

On less smoky days, the number of workers in the areas studied was nearly 18% below typical levels and hours worked 23% below normal, according to a new study from the University of California, Davis, published in the January issue of the journal is the Association of Environmental and Resource Economists.

“If this smoke is really strong, the number of people in a field per day is significantly reduced,” said Tim Beatty, chair of the Department of Agricultural and Resource Economists and senior author of the study.

The researchers also found that farmworkers tended to work longer hours and change fields in the days before smoke events to avoid the worst conditions.

“We were able to obtain very rich hour-by-hour information about where these farmworkers went and whether they moved to another location,” said Goeun Lee, a postdoctoral researcher and lead author of the journal. “This is, so to speak, the first application of these data to answer some important questions in agricultural economics.”

A new resource

The research represents a new way to gather information about one of California’s most elusive workforces – agricultural workers who harvest crops that help feed the country – that traditional sources cannot quantify.

“The results are relevant for policymakers who want to protect the health, safety and well-being of workers and ensure the sustainability of one of the most productive agricultural regions in the world,” the authors write.

Lee and Beatty used field boundaries to define the locations of agricultural crops, overlaid smoke clouds and weather data to determine environmental conditions, and accessed cell phone data from a company that collects location information from about 400 mobile applications.

They identified field-level time, location and movement data from cell phones from January to mid-October for 12,667 harvest workers — representing 8% of California’s agricultural workforce — and a sample size 20 times larger than the state’s National Agricultural Worker Survey from 2020, providing an important but limited point resource for tracking this population.

“We don’t do a good job of collecting data on these fairly marginalized groups that are very important, so it’s very difficult for us to say anything about policies that affect them because they don’t show up in the data,” Beatty said. “This mobility data is interesting and important to really answer questions about a group of people who are underrepresented in surveys.”

Shocks on the horizon

Large wildfires and other environmental disasters are expected to become more common, and current protective measures may not be enough to protect farmworkers and their financial health, the authors said.

“Agricultural workers work primarily outdoors and are exposed to many environmental influences and factors that can negatively impact their health and productivity,” Lee said. “Climate change is expected to increase the frequency of wildfire smoke, and California relies heavily on this workforce. They are essential to California agriculture.”

Wildfire smoke can cause fatigue, dizziness, headaches, confusion and other symptoms that increase the risk of injury. The researchers defined days with high smoke levels as days with 40 micrograms of fine dust per cubic meter. California regulations require workers to wear protective equipment such as respirators, change their schedule or work in an area with better air quality if particulate matter levels are 55.5 micrograms per cubic meter.

The short harvest season coincides with more intense wildfire months, meaning farmworkers could take a hit in wages while avoiding the risk of smoke. “We should be concerned about people’s health, but also their ability to earn a living, because that also has a very direct impact on their health and well-being,” Beatty said.

Future studies

The research has some limitations regarding who made smoke-related decisions.

“It could be as simple as farmers having multiple fields and simply changing the field they want to harvest that day. It could be that they work for an agricultural contractor and they just change the client they work for that day,” Beatty said. “That sets the table for a lot of future questions.”

The methodology could be used to answer future labor, environmental and agricultural economics questions. The authors use cell phone data to track the movements and behavior of agricultural workers during extreme heat events and after pesticide use.

“This new dataset we created can be a valuable resource for answering other questions about farmworkers,” Lee said.

The research was funded by the USDA National Institute of Food and Agriculture.