Air quality in the San Joaquin Valley (SJV) often fails to meet Environmental Protection (EPA) Standards for particulate matter (PM) ≤ 2.5 microns. The San Joaquin Valley Center for Air Injustice Reduction (SJV-CAIR) at the University of California, Merced, partnered with local community-based organizations to expand networks of low-cost air quality monitors (PurpleAir, PA-II) in Fresno County to increase community air monitoring to better characterize air pollution trends and spatial variability. In this study, we compared community and regulatory air pollution monitoring using PM_2.5 data from the SJV-CAIR network in Fresno County during June–July 2023. Measurements from community monitors identified locations across the county that may episodically exceed National Ambient Air Quality Standards (NAAQS) compared with regulatory monitors, while providing similar concentration estimates. Our study also compared characterization of spatial variability in PM exposure using interpolation maps with only regulatory monitors and the enhanced community monitoring network. These analyses identified four weeks with increased PM_2.5 concentrations in some locations that were not identified by regulatory monitors. These findings indicate that low-cost community sensors can be an effective tool for supplementing regulatory monitoring to provide localized PM_2.5 exposure information to residents and, importantly, identify high-risk areas that warrant ongoing assessment using approved regulatory monitors.

Air quality in the San Joaquin Valley (SJV) ranks among the worst in the US. Exposures to traffic-related air pollutants have been associated with pediatric health complications, and few studies have investigated respiratory complications in relation to short-term exposures to PM less than 2.5 microns in diameter (PM_2.5) in the SJV. We used Bayesian Poisson spatiotemporal conditional autoregressive models to analyze the association between PM_2.5 and pediatric respiratory emergency department (ED) visits in Fresno County, California. Additional analyses stratified respiratory outcomes by sex and age group. Weekly ambient PM_2.5 levels were estimated for each zip code using community science and regulatory air monitors. Weekly residential zip code counts of respiratory ED visits were provided by Fresno County Department of Public Health and Valley Children’s Hospital from 2 April 2022 to 31 December 2024. A ten-fold increase in PM_2.5 was associated with increased asthma ED visits among females (Relative Risk (RR):1.15; 95% Credible Interval (CrI):1.01, 1.32) and children aged 0 to 4 (RR:1.18; 95% CrI:1.03, 1.34) and other chronic respiratory conditions among males (RR:1.93; 95% CrI:1.19, 3.16) and ages 10 to 14 (RR:2.90; 95% CrI:1.32, 6.30). Findings suggest that efforts to better assess and reduce pollution exposures will improve public health in the SJV.

Indoor nitrogen dioxide (NO2) and fine particulate matter (PM2.5) pollution is a concern in U.S. households, particularly those that cook using gas or propane stoves. These exposures are linked to a variety of adverse health outcomes, including asthma morbidity, that disproportionately affect low-income households. We conducted a cross-sectional study of 138 homes in four low-income rural communities in California’s San Joaquin Valley, comparing air pollutant concentrations in households that participated in a state electrification program against those using propane or natural gas for cooking. In each home, pollutants were monitored for approximately one month using Personal Air Monitors (PAMs) and for 48 hours using reference-grade instruments. Median 48-h average indoor NO2 concentrations were 63% lower in electric stove homes (electric: 6.0 ppb, gas: 16.0 ppb, p < 0.001). No electrified homes had 48-h indoor NO2 concentrations exceeding the California annual guideline of 30 ppb, while 17% of gas homes did. Additionally, no electric stove homes had 1-h rolling-average NO2 concentrations exceeding the 100 ppb level deemed unhealthy for sensitive groups by the US Environmental Protection Agency, whereas 41% of gas homes exceeded this threshold. PM2.5 concentrations were similar across groups, indicating that the cooking of food was the dominant contributor to PM2.5 mass concentrations, as opposed to particles generated from gas combustion. Our evaluation of monitoring durations showed that two to four days of NO2 data and one week of PM2.5 data provided reliable estimates of longer-term averages, suggesting that shorter campaigns may yield robust estimates of indoor air quality. These results (1) support the provision of electric cooking technologies as a strategy to address air quality-related health risks in rural, low-income communities and (2) provide new evidence from an understudied population that can inform future indoor air quality research and energy transition policies.

The San Joaquin Valley in California has some of the nation’s worst air quality. Health effects from elevated outdoor air pollution may be compounded by poor indoor air quality due to use of certain consumer products or individual activities. The BiomSPHERE study measured air pollution-related urinary exposure biomarkers in residents of Stockton and Fresno, California. Urine samples were collected from 64 adult–child pairs in 2023. Metabolites of four polycyclic aromatic hydrocarbons (PAHs) and five volatile organic compounds (VOCs) were measured in urine. Questionnaires were administered to collect information on demographics and potential exposure sources. Metabolites of all PAHs (fluorene, naphthalene, phenanthrene, and pyrene) and four VOCs (acrolein, acrylonitrile, crotonaldehyde, and propylene oxide) were detected in >85% of the samples. 2-Hydroxynaphthalene (2-NAP) was the only PAH metabolite that had higher concentrations in BiomSPHERE adults and children compared with nationally representative levels reported by the U.S. National Health and Nutrition Examination Survey (NHANES). Concentrations of 2-NAP were significantly correlated (p < 0.05) between adults and children, suggesting a common exposure source. Concentrations of 2-NAP were also significantly higher among Hispanic/Latino participants and among participants who recently used cleaning products, air fresheners, and scented personal care products (p < 0.05). For non-smoking adults, metabolites of the VOCs acrolein, acrylonitrile, and propylene oxide were significantly higher in BiomSPHERE compared with NHANES. Further research is needed to identify the sources of elevated 2-NAP and VOC urinary metabolite concentrations.