Hero Image

Produce Safety after Urban Wildfire

Post Fire Food Safety Community Science Study

Urban Wildfire and Potential Contamination 

The fires that spread through Northern California in October 2017 burned over 160,000 acres of wildland, suburban, urban and industrial areas, creating dangerous air quality conditions for the region that lasted long beyond the fires themselves. The wildfire smoke likely included high concentrations of toxic air contaminants.[1] Following the fires, the Food and Drug Administration wrote a letter to the California Department of Food and Agriculture and the California Department of Public Health, stating that “toxic elements, firefighting chemicals, and combustion products such as polycyclic aromatic hydrocarbons (PAHs) and dioxins are of greatest concern.” There are well-known human health impacts from the inhalation of these contaminants. Additionally, plants have the potential to absorb air pollutants directly through their leaves,[2],[3],[4] but little research has been done on the risk to human health from ingesting contaminants from smoke and ash on produce.

Impact on Local Farms, and Gardens, and Backyard Poultry

Local farms and gardens played a significant role in food relief efforts immediately following the October 2017 wildfires, contributing produce to shelters and kitchens. Many farmers, gardeners, and community members were concerned about how the fire-related air pollution might impact locally-grown produce. Farmers were unsure of the potential health impacts of the fire on themselves, their workers, and their customers. School, community and home gardeners were concerned about the potential health impact on children and other vulnerable groups. 

The UC Davis School of Veterinary Medicine (UCD SVM) provided free egg contaminant testing for backyard chicken owners in the state of California from January to September 2018. Eggs were tested for two different types of contaminants, depending on what county the hens resided in. For more information on this study, go to: Egg Study Results.

Community Citizen Science Initiative

In the weeks following the October 2017 Sonoma County fires, concerned community members came together to launch the Produce Safety after Urban Wildfire Citizen Science Initiative. Sonoma County residents and members of the UC Master Gardener Program of Sonoma County collaborated to take samples from over 25 sites across the county using a sampling protocol created under advisement by Environmental Health and Food Safety Specialists. Samples included washed and unwashed produce, each in triplicate, to determine if contaminants were present and whether contaminants could be easily washed off produce. Volunteers focused on leafy greens with large surface area directly exposed to air pollution: kale, collards, chard, and lettuce. In total, over 200 samples were taken and frozen for subsequent laboratory analysis.

Soil contamination was also a concern for the community, and thus, community-led soil sampling at high priority sites was conducted in June 2018 to test for persistent chemicals at 7 months following the fires. 


Online Toolkit - Produce Safety After Urban Wildfire

In the weeks following the October 2017 Sonoma County fires, concerned community members came together to launch the Produce Safety after Urban Wildfire Citizen Science Initiative. This tool kit is designed for communities experiencing urban wildfire to conduct their own community-based research on the safety of local produce, backyard chicken eggs and soil as well as to provide background educational resources about the results of our study, the potential health impacts of urban wildfire smoke, and how to reduce risk.  We hope more groups experiencing urban wildfires will expand emerging research on this topic by adapting this citizen science research initiative for your specific communities.   

This online toolkit contains links to the following resources based on topic areas:

Overview of the project

Conducting your own community research

Testing & Analyzing Samples

  1. The list of chemicals that we considered and what we tested 
  2. Site and neighborhood history, what new contaminants might have entered, what existing contamination might be aggravated
  • List of resources for doing your site history research
    1. Determine Budget
    2. Determine the capacity of the lab
    3. Finalize your list of contaminants
  • Analyzing Results:
    1. Considerations for analyzing your results from the lab -- how to decide what to test for, site history, etc.
    2. Prop 65 NSRL -- refer to final report

Community Outreach

Results from our study of the fires in Santa Rosa in 2017


MediaNews & social media reports on our project: 


Thank you to all the volunteers who contributed time and resources to this community research initiative and to all the farms and community gardens who provided produce from their sites to be tested!

As a citizen science project, this study depends on you, and in return, we are committed to staying in touch with you about the results from this study and the next steps we can take as a community.

Stay connected:


Our Community Citizen Science project invites and is still seeking researchers, advisors, and collaborators to continue to study the impact of urban wild the North Bay fires on the local produce food safety of local produce., We hope this work will continue to support from a cumulative health perspective. We are seeking collaborators with substantial experience in their fields who can weigh in as advisors, as well as graduate students and researchers who can lend substantial capacity- such as long-term collaboration for publications and thesis or dissertation work.

Above all: we are seeking researchers with a desire to research these questions in a holistic way that that takes into account the value of local growers for a resilient economy, takes into account the health benefits of accessing fresh produce and the larger context of chemical contamination of the mainstream food system, and prioritizes collaboration with the local community.

If you have these or other skills and have capacity to lend, please contact us at menright@ucanrucdavis.edu


[1] Lemieux, Paul M. "Emissions of Organic Air Toxics from Open Burning." Washington, DC, United States Environmental Protection Agency 62 (2002).

[2] Uzu, Gaëlle, et al. "Foliar lead uptake by lettuce exposed to atmospheric fallouts." Environmental Science & Technology44.3 (2010): 1036-1042.

[3] Kipopoulou, A. M., E. Manoli, and C. Samara. "Bioconcentration of polycyclic aromatic hydrocarbons in vegetables grown in an industrial area." Environmental pollution 106.3 (1999): 369-380.

[4] Schreck, Eva, et al. "Metal and metalloid foliar uptake by various plant species exposed to atmospheric industrial fallout: mechanisms involved for lead." Science of the Total Environment 427 (2012): 253-262.