Distance to a Drying Saline Lake and Lung Function Development in a Rural Border Cohort of Children.

Importance: The Salton Sea, a drying saline lake in southeastern California, is a growing source of wind-blown dust. Its long-term impact on children's lung function growth remains unclear. Objective: To investigate the association of proximity to the Salton Sea and dust exposure with children's lung function growth trajectories. Design, Setting, and Participants: For this longitudinal cohort study, community-engaged research was conducted in Imperial Valley, California, in partnership with Comité Civico del Valle, a long-standing local community organization. Children in first to third grades from 5 elementary schools near the Salton Sea were invited to participate between May 1, 2017, and May 27, 2019. Participants with missing data on core variables or with only 1 spirometry measure were excluded from analysis. Lung function assessment was conducted from March 22, 2019, to July 25, 2022; data analyses were conducted from July 2024 to July 2025. Exposures: The primary exposure was the distance from each child's home to the edge of the Salton Sea, with residence near the sea defined as less than 11 km. Secondary exposures included particulate matter (PM) and dust storm hours (PM10 > 150 µg/m3), estimated using data from regulatory monitors. Main Outcomes and Measures: Lung function was assessed via spirometry (forced expiratory volume in 1 second [FEV1] and forced vital capacity [FVC]). Covariates included age, sex, ethnicity, socioeconomic status, height, body mass index, baseline respiratory health, and asthma status. Results: Of 499 children enrolled, 369 were included in the final analysis (205 [55.6%] female and 164 [44.4%] male), with a mean (SD) baseline age of 10.1 (0.6) years and mean (SD) follow-up of 2.0 (1.0) years, contributing a total of 1146 spirometry measurements (approximately 3 per participant). In fully adjusted mixed effects models, living near the sea (<11 km) was associated with 52.18 mL/y lower FVC growth (95% CI, -100.96 to -3.40 mL/y; P = .04), compared with living farther from the sea. The association with FEV1 did not reach statistical significance. More hours of dust event exposure were associated with lower FVC (β = -4.10 mL/y; 95% CI, -7.55 to -0.75 mL/y) and FEV1 growth (β = -2.26 mL/y; 95% CI, -4.22 to -0.29 mL/y), with a stronger association between dust event and FVC observed among children living near the sea (P for interaction = .04). Conclusions and Relevance: In this cohort study of school-aged children, closer residential proximity to the Salton Sea was associated with reduced lung function growth. These findings underscore the need to address environmental degradation in the region to protect children's respiratory health.