US Air Quality Index and respiratory health outcomes: background, knowledge gaps, and research prioritization: an Official American Thoracic Society Research Statement

BACKGROUND: The US Air Quality Index (AQI) is the most widely reported tool for public communication of air pollution health risks in the United States, yet its effectiveness in protecting individuals with respiratory conditions remain poorly understood. GOALS: The American Thoracic Society (ATS) convened an ad hoc multidisciplinary committee, including participation from relevant officials, to assess the current evidence and define research priorities related to the AQI and respiratory health. METHODS: The committee conducted a systematic search of the peer-reviewed literature and held a meeting to discuss key topics. Subsequent engagement refined the findings and established consensus on priority research questions. RESULTS: The systematic search indicated significant gaps in the literature, including limited evaluation of AQI effectiveness in changing behavior, few studies assessing health outcomes associated with AQI use, and minimal research on how people with respiratory disease interpret and respond to AQI messaging. Priority research areas span key domains: AQI structure, sub-daily exposure estimation, communication strategies, clinical and community implementation, and evaluation of health and exposure reductions. Specific research recommendations include evaluating AQI structures that better reflect cumulative and multi-pollutant exposures, developing methods to assess how patients with respiratory conditions interpret and act on AQI messaging, and measuring whether AQI-informed behaviors result in meaningful reductions in exposure and improvements in health outcomes. CONCLUSIONS: This research statement outlines a framework for strengthening the scientific foundation of the AQI and improving its effectiveness as a respiratory health protection tool.