Air quality monitoring and the safety of farmworkers in wildfire mandatory evacuation zones
By Michael Méndez and Carlo Chunga Pizarro
In Sonoma County, there is growing concern for environmental justice and labor rights during extreme wildfire events and those subjected to Sonoma’s Agricultural (Ag Pass) program. Our previous research highlighted the program’s lack of oversight, emergency and occupational safety protocol inconsistencies, and insufficient farmworker monitoring of hazardous air quality in the impacted regions. This offered us data to analyze further the air quality risks, health impacts, and structural inequalities the program imposes on farmworkers, particularly those who are undocumented.
In 2019, the California Occupational Safety and Health Standards Board (Cal/OSHA) adopted an emergency regulation (CCR § 5141.1) requiring employers of outdoor workers to provide respiratory masks when the Air Quality Index (AQI) due to PM2.5 exceeds 150 (i.e., PM2.5 > 55.5 μg m−3) for more than 1 hr. 11, 12 An AQI above 150 corresponds to the United States Environmental Protection Agency's (US EPA) "unhealthy" health hazard level." Research indicates the need for improvement and standardization in these systems, particularly air quality monitoring. In Sonoma County, the sole wildfire smoke for PM2.5 monitor, AirNow, is in Sebastopol, where conditions may not represent the air quality at individual job sites throughout the county (often miles away). Therefore, we explore the use of the low-cost PurpleAir monitor network, which collects and shares PM2.5 data for public use. The number of PurpleAir monitors brought online in wildfire-prone regions has increased rapidly in recent years, likely due to residents' growing concern over worsening air quality. California and the Sonoma County region have the highest technology adoption in the country.
Our research examines:
- How effective are current air quality monitoring systems (e.g., EPA's AirNow and PurpleAir) in assessing wildfire smoke exposure in Sonoma County, and what are the implications for worker safety and public health?
- What policy recommendations can be made to improve the protection and safety of agricultural workers during wildfire events, considering the shortcomings in the Ag Pass system and air quality monitoring?
Results & Key Findings
Our research, which compared data from the AirNow monitor in Sebastopol with smoke-corrected data from 359 PurpleAir monitors across Sonoma County from July 31 to November 6, 2020, is of significant importance. The study focused on regions affected by the LNU Complex and Glass fires, providing crucial insights into air quality during these wildfire events.
During this period, the WHO PM2.5 guideline (15 µg/m³) was exceeded on 18 days, according to AirNow data, and on 34 days, according to PurpleAir data. PurpleAir monitors recorded PM2.5 levels above the EPA thresholds for "Unhealthy for Sensitive Groups" (35.5 µg/m³) and "Unhealthy" (55.5 µg/m³) more frequently than AirNow. PurpleAir data near Sebastopol correlated strongly with AirNow, though PurpleAir showed slightly lower PM2.5 levels.
Analyzing air quality in Ag Pass regions, we identified significant variations. PurpleAir monitors in the LNU Complex and Glass Fire areas showed higher and more variable PM2.5 levels than the AirNow monitor in Sebastopol. During the LNU Complex fires, PM2.5 levels in the Ag Pass region often surpassed the "Unhealthy" threshold, while the AirNow monitor showed lower levels.
Our research, which also noted higher PM2.5 levels during the glass fire, particularly significant for night-time grape harvests, underscores the urgency of the situation. It highlights the inadequacy of relying on a single AirNow monitor, emphasizing the critical need for a comprehensive monitoring system to protect public health during such events.
PurpleAir data provides a more complete picture of pollution levels, underscoring the need for improved air quality monitoring and protective measures for outdoor workers.
Key Findings
- Air quality was UNHEALTHY on 4 more days during the Glass fire, but 1 less during LNU Fire, when Ag Passes were issued. On multiple occasions, smoke levels remained high overnight, with PM2.5 exceeding levels considered unhealthy or worse.
- PM2.5 levels often exceed the World Health Organization’s 15 μg/m³ air quality guideline, highlighting the health risks associated with wildfire smoke.
- The graphs show EPA thresholds for PM2.5, making levels harmful to sensitive groups and the general public.
- During the LNU complex and Glass Fire events, PM2.5 levels spiked, demonstrating the severe impact of these fires on air quality.
- The county-wide average PM2.5 from PurpleAir monitors generally tracked the AirNow monitor’s readings but with more significant variability, underscoring the importance of having multiple monitoring points to accurately assess air quality across different regions.
Policy Recommendations
- Mandatory Employer Emergency Plans and Training
Employers should be required to create comprehensive emergency plans to protect outdoor workers. Collaborative protocols should be developed with emergency response agencies and farmworkers' rights groups to ensure efficient evacuation. Farmworkers should be offered training in multiple languages on disaster awareness, health and safety issues, entrapment avoidance, fire behavior, and collaboration with emergency personnel. - Improve Protocols on Identifying Workers and Locations
Accurate documentation of the number of workers entering worksites and the location of each site is necessary for safety. This information should be readily accessible to emergency personnel. Regular visits to previously accepted permit locations should be conducted to keep information up to date and ensure worker safety. - Real-Time Local Air Quality Monitoring
Local real-time air quality monitors should be placed within worksites to provide farmworkers, employers, and policymakers with more accurate and timely information on air quality. This will enable informed decisions regarding the use of Ag Pass permits and access to mandatory evacuation zones. This is particularly important when local air quality monitors indicate hazardous events not reflected in the nearest regulatory AirNow monitor. - Provide Hazard Pay
In recognition of the Ag Pass program's risks to agricultural workers, employers should provide time-and-a-half hazard pay. This should be instituted for a complete 6-hour shift if the AQI is above 150 at any point within the previous 24 hours, a level considered unhealthy for everyone. Notably, three wineries in Sonoma and Napa Counties have agreed to such terms in recent labor contracts. 15, 16 - Post-Exposure Health Screening
State and County governments and employers should work together to provide funding to workers for post-exposure healthcare and well-being monitoring. These screenings should include initial health assessments, ongoing medical check-ups, and specialized tests focused on respiratory functions and potential toxicological effects of smoke inhalation. Additionally, regular health check-ups and mental health evaluations are essential to detecting early signs of smoke-related illnesses and addressing mental health impacts. 17 Defining wildfire smoke exposure, based on intensity and duration, would ensure targeted and effective health intervention. - Post-Incident Accountability and Data Transparency
Following wildfire events during which Ag Passes are issued, the County should thoroughly evaluate the program's accuracy and effectiveness. This analysis is critical for ensuring compliance and assessing the program's implementation risks. The resulting data and analysis should be publicly available to enhance transparency and enable future research.
The policy brief is available for download, and the research paper is available at GeoHealth.