Urban Air Pollution and Emergency Department Visits for Neoplasms, Hematologic, and Metabolic System Disorders

Numerous studies have linked short-term exposure to ambient air pollution with cardiopulmonary health outcomes, yet evidence regarding other health conditions remains limited. This study investigates associations between urban air pollutant concentrations and emergency department visits for a broader spectrum of health outcomes classified under ICD-10 Chapters II (neoplasms), III (blood diseases), IV (endocrine and metabolic disorders), and XVIII (symptoms and signs). Using a case-crossover design with conditional Poisson regression, relative risks were estimated for pollutant exposures, particularly nitrogen dioxide (NO₂), across multiple lag periods up to 14 days. The analysis incorporated stratified subgroup estimates, applying dynamic linear models and a novel transformation of pollutant concentration to better characterize concentration–response relationships. Results demonstrate consistent positive associations between NO₂ levels and emergency visits across all studied chapters, with the strongest effects observed within 0 to 3 days after exposure. While cumulative concentration–response functions were not computed due to data limitations, the methodology presented offers a flexible framework for modeling temporal risk patterns. These findings suggest that air pollution impacts a wider range of health outcomes than traditionally recognized, highlighting the need for broader consideration in environmental health research and public health policy.