Association between daily variations in the levels of atmospheric O3, PM2.5, and NO2 and the frequency of hospital visits due to respiratory diseases and hypertension in Mexico City using Generalized Additive Mixed Models

Elizabeth Vega^1*Alejandro Ruiz-Olivares²Yosune Miquelajauregui³Regina Rentería-Campos⁴Lindsay Bramwell⁵Romain Bernard M. Feytmans⁴Anil Namdeo⁵Juan Carlos Núñez-Enríquez⁶Jane A Entwistle⁵Mónica Jaimes-Palomera⁷Nancy Minerva Torres-Rojas⁸R Alberto Rascón-Pacheco⁹David A Duarte- Rodríguez⁶Richard JQ McNally¹⁰Jimena García-Burgos¹¹Cinthia Gabriela Resendiz-Martinez¹²Ángel Fragoso-Chino¹²Louise Hayes¹⁰Antonio Portas¹³Juan Manuel Mejia-Arangure^14*

• ¹Instituto de Ciencias de la Atmósfera y Cambio Climático, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico, CDMX, Mexico
• ²Department of Soil Sciences, Colegio de Postgraduados, Montecillo 56231, Mexico, Estado de Mexico, Mexico
• ³Laboratorio Nacional de Ciencias de la Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México (UNAM), Mexico City 04510, Mexico, CDMX, Mexico
• ⁴Facultad de Medicina, Universidad Anáhuac México Sur, Mexico City 01840, Mexico, CDMX, Mexico
• ⁵Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UK, Newcastle, United Kingdom
• ⁶Unidad de Investigación Médica en Epidemiología Clínica, UMAE Hospital de Pediatría Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico City 06720, Mexico, CDMX, Mexico
• ⁷Dirección de Monitoreo de Calidad del Aire, Secretaria del Medio Ambiente, Gobierno de la Ciudad de Mexico, Mexico City, Mexico, CDMX, Mexico
• ⁸Coordinación de Vigilancia Epidemiológica, Instituto Mexicano del Seguro Social, Mexico City, Mexico, CDMX, Mexico
• ⁹Unidad de Educación, Investigación y Políticas de Salud, Instituto Mexicano del Seguro Social, Ciudad de Mexico, Mexico, CDMX, Mexico
• ¹⁰Population Health Sciences Institute, Newcastle University, Newcastle upon Tyne, UK, Newcastle, United Kingdom
• ¹¹Laboratorio de Ecología, Unidad de Biología de la Conservación, Parque Científico y Tecnológico de Yucatán, Universidad Nacional Autónoma de México (UNAM), Mérida 97302, Mexico, Mérida, Mexico
• ¹²Secretaría de Medio Ambiente de la Ciudad de México, Mexico City 06068, Mexico, CDMX, Mexico
• ¹³Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne NE7 7XA, UK, Newcastle, United Kingdom
• ¹⁴Genomica Funcional del Cancer, Instituto Nacional de Medicina Genomica & Facultad de Medicina, Universidad Nacional Autonoma de Mexico, Mexico, Mexico

Background: Environmental pollution is a significant public health issue in Mexico City. Patients with respiratory or cardiovascular diseases, such as asthma or hypertension, often experience exacerbations triggered by environmental factors. This retrospective time series epidemiological study analyzed the association between daily air pollution levels and the number of medical visits for exacerbations of cardiorespiratory diseases. Methods: Records from primary, secondary, and tertiary hospitals of the Mexican Institute of Social Security (IMSS) were reviewed between 2017 and 2019. Air quality data, including PM2.5, PM10, O3, and NO2 concentrations, were collected hourly from air quality monitoring stations at fixed sites. To fit the models and take into account temporal autocorrelation and the complex non-linear relationships between pollutants and cardiorespiratory diseases, Generalized Additive Mixed Models (GAMM) were applied. Results: PM2.5, O3, and NO2 exposure showed a strong association with an increase in visits for upper respiratory diseases. Age was a relevant factor: individuals aged between 19-35 years were the most affected, whereas those aged 66-100 years were the least affected. An effect on the weekdays was identified, with peaks in visits on Mondays and decreases on Saturdays. Also, seasonally, results showed an increase in October and decline in August. Regarding hypertensive diseases, only PM2.5 exhibited an association. The models confirmed the link between air pollution levels and respiratory disease exacerbations, highlighting key public health implications. Conclusion: This study provides strong evidence that short-term exposure to elevated concentrations of atmospheric pollutants, specifically PM2.5, O3, and NO2, are significantly associated with an increase in medical visits for upper respiratory diseases, asthma, and hypertension in Mexico City. By employing Generalized Additive Mixed Models and analyzing health records from IMSS-affiliated hospitals between 2017 and 2019, we observed that the effects of air pollution varied by disease, age group, season, and day of the week.