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Stockton Air Pollution Exposure Project (SAPEP)

Study of air pollution exposures in school children in Stockton

A jigsaw puzzle of a school with the words Stockton Air Pollution Exposure Project

The Stockton Air Pollution Exposure Project (SAPEP) is a collaboration with the University of California (Berkeley CERCH, Merced, and San Francisco), Little Manila Rising, and All Saints Academy of Stockton. Stockton, an AB 617 community, is heavily impacted by air pollution exposures, with a CalEnviroScreen rank in the top 5% for overall pollution burden and diesel particulate matter. This community is also burdened by economic, social, and health inequities.

Eighteen children from the All Saints Academy of Stockton were enrolled in the study. Participants were predominantly Hispanic/Latino. To help with urine collection and exposure questionnaires, one parent/guardian was also enrolled in the study. A total of sixty-nine urine samples were collected before school and after school on two days during the weeks of December 6 and 13, 2021.

Collecting samples at multiple time points allowed us to better understand children’s exposures to these pollutants. Metabolites of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs), including naphthalene, were measured in the urine samples. These metabolites may indicate exposure to air pollutants. To help us interpret the biomonitoring results, air quality was measured inside the school and at outside locations on school grounds. Purple Air monitors were used to measure PM2.5 and air samples were analyzed for select PAHs and VOCs.

Biomonitoring results for the child participants were sent to parents who requested them, along with information on actions families can take to reduce their air pollution exposures. Staff members also presented a summary of study findings to the school and the larger Stockton community.

Tipo de proyecto:

Full project collaboration

Estado del proyecto:

Ongoing

Participantes:

18 children

Fecha de la toma de la muestra:

Zona de la toma de la muestra:

Stockton, California

A summary of PAH and VOC metabolite levels among SAPEP participants was published in Frontiers in Public Health on April 9, 2026.

Some key findings include:

  • Naphthalene metabolite levels in SAPEP were nearly three times higher than national average levels in children.
  •  Metabolite levels for most other PAHs and VOCs in SAPEP were found to be similar to, or lower than, those in US children.
  • Air pollution doesn't appear to be the main source of exposure, so other naphthalene exposure sources should be examined.

Our findings highlight the need for further research to monitor trends and investigate novel exposure sources of naphthalene and its metabolites, especially in children who are likely to be more susceptible to naphthalene.

Biomonitoring data from other US studies suggest naphthalene exposures may be increasing, particularly in Hispanic/Latino communities.

Hurley S, Castorina R, Sultana D, Thompson M, Jarmul S, Gunier RB, Nirula A, Ortiz-Pivaral L, Jacob P, She J, DeGuzman J, Garcia-Jauregui N, Holmes M and Bradman A (2026) High levels of urinary naphthalene metabolites measured in a sample of California schoolchildren: a call to expand monitoring and identify exposure sources. Front. Public Health 14:1789602. doi: 10.3389/fpubh.2026.1789602

Presentations at Scientific Guidance Panel (SGP) Meetings:

Additional Project Information:

Published Findings in Scientific Journals:

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