Health Impacts, Regulatory Frameworks, and Clinical Coding Guidelines for PM2.5 Exposure in Thailand

Abstract

Background: Fine particulate matter with an aerodynamic diameter of less than 2.5 micrometers (PM2.5) represents a critical environmental health risk factor. The World Health Organization (WHO) estimated that exposure to PM2.5 contributes to approximately 4-9 million premature deaths worldwide and 25,432 deaths annually in Thailand. Despite these severe impacts, statistical surveillance and the enforcement of regulatory frameworks in Thailand remain limited. Objective: To review scientific evidence regarding the health impacts of PM2.5 exposure within the context of occupational and environmental medicine; to analyze legal frameworks and ambient air quality standards in Thailand; and to identify clinical diagnosis and coding methods to enhance the statistical accuracy of tracking affected populations. Methods: A narrative literature review was conducted using PubMed and Scopus Databases, alongside relevant government policy documents published up to 2026. Results: PM2.5 exposure is significantly associated with various disease groups, while Thailand's annual average PM2.5 levels consistently exceed standard guidelines. In clinical practice, challenges persist in both differential diagnosis and the under-coding of co-morbidities. This article identifies guidelines for utilizing code Z58.1 (Exposure to air pollution) alongside code Y97 (Environmental-pollution-related condition) as secondary codes in health database systems. Conclusion: All physicians, alongside occupational and environmental medicine specialists, play a pivotal role in diagnosing PM2.5-related illnesses and supporting policy advocacy. Utilizing precise diagnostic data to generate robust health statistics is essential for driving sustainable public health policies and protecting the population from the hazards of PM2.5.