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.

Incense and candle burning, deeply rooted in cultural and aesthetic practices, are increasingly recognized as a significant source of indoor air pollution. The present study employed spectrometry‐based techniques to characterize candle and incense emissions at the molecular level, focusing on diethyl phthalate (DEP), a widely used plasticizer raising concerns over its endocrine‐disrupting and neurotoxic effects. Experiments were conducted under controlled chamber conditions and in realistic indoor environments to quantify DEP emission factors, temporal profiles, chemical stability, and phase partitioning. As the dominant ester species, DEP was consistently detected across all samples examined, comprising on average ~18.8% and ~2.4% of the identified molecular features in incense and candle aerosols, respectively. Moreover, DEP demonstrated sustained stability under acidic and photolytic conditions, suggesting its persistence in indoor environments. Notably, incense smoke retained DEP primarily in the particle phase, whereas candle emissions exhibited a more dynamic distribution yet still maintained a particle fraction exceeding 80%. These results contrast with other household sources that primarily release DEP as vapors, implying that combustion‐derived DEP poses a greater exposure risk due to its efficient pulmonary deposition in particle‐bound form. A further exposure assessment integrating our airborne measurements with literature data revealed that inhalation is the dominant exposure pathway, exceeding the combined intake from dermal absorption and ingestion by nearly an order of magnitude. This dominance driven primarily by incense emissions underscores the need for further investigation into the long‐term health risks associated with chronic DEP inhalation.

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.