The Impact of Ambient Ozone Exposure on Respiratory Health in the U.S. Populations: A Systematic Review.

Ozone, a photochemically generated air pollutant, continues to pose a major concern for public health in the United States, with some 125 million people living in areas that exceed national ambient air quality standards set by the United States Environmental Protection Agency. To fully understand the potential impacts of ambient ozone exposure on respiratory health, we conducted a systematic review of United States epidemiologic and experimental studies published from 1980 to 2026, encompassing both acute and chronic exposure windows. This review focused on three key domains: (1) pulmonary function, (2) asthma-related symptoms and emergency department visits/hospitalizations, and (3) other respiratory-related morbidity and mortality. Findings across diverse study designs demonstrated adverse respiratory effects, with children, older adults, and individuals with pre-existing respiratory conditions being disproportionately affected. This review is among the first to comprehensively synthesize ozone-related respiratory health outcomes including pulmonary functions outcomes across both experimental and population-based observational studies-highlighting consistent decrements in lung function, even at concentrations below current regulatory standards. Additionally, this work incorporated ozone-associated school absenteeism, a sensitive yet underexamined indicator for pediatric respiratory health outcome. The observed associations across multiple outcomes and exposure durations underscored the importance of strengthening ambient air quality standards and prioritizing interventions toward high-risk populations. Continued increases in ambient ozone exposure even in the presence of regulatory action and increasing contributions from sources related to climate change such as wildfires emphasize the importance of sustained research and public health planning to safeguard respiratory health in vulnerable communities.