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 Vega1*, Alejandro Ruiz-Olivares2, Yosune Miquelajauregui3, Regina Rentería-Campos4, Lindsay Bramwell5, Romain Bernard M. Feytmans4, Anil Namdeo5, Juan Carlos Núñez-Enríquez6, Jane A. Entwistle5, Monica Jaimes-Palomera ́ 7, Nancy Minerva Torres-Rojas8, R. Alberto Rascon-Pacheco ́ 9, David A. Duarte-Rodríguez6, Richard J. Q. McNally10, Jimena García-Burgos11, Cinthia Gabriela Resendiz-Martinez12, ́Angel Fragoso-Chino12, Louise Hayes10, Antonio Portas13 and Juan Manuel Mejia-Arangure14*

1. Instituto de Ciencias de la Atmósfera y Cambio Climático, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
2. Department of Soil Sciences, Colegio de Postgraduados, Montecillo, Mexico
3. Laboratorio Nacional de Ciencias de la Sostenibilidad, Instituto de Ecología, Universidad Nacional Autónoma de México (UNAM), Mexico City, Mexico
4. Facultad de Medicina, Universidad Anáhuac México Sur, Mexico City, Mexico
5. Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
6. Unidad de Investigación Médica en Epidemiología Clínica, UMAE Hospital de Pediatría Siglo XXI, Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico
7. Dirección de Monitoreo de Calidad del Aire, Secretaria del Medio Ambiente, Gobierno de la Ciudad de Mexico, Mexico City, Mexico
8. Coordinación de Vigilancia Epidemiológica, Instituto Mexicano del Seguro Social, Mexico City, Mexico
9. Unidad de Educación, Investigación y Políticas de Salud, Instituto Mexicano del Seguro Social, Ciudad de Mexico, Mexico
10. Population Health Sciences Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
11. Laboratorio de Ecología, Unidad de Biología de la Conservación, Parque Científico y Tecnológico de Yucatán, Universidad Nacional Autónoma de México (UNAM), Mérida, Mexico
12. Análisis y Modelación de Calidad del Aire, Secretaría de Medio ambiente de la Ciudad de México, Mexico City, Mexico
13. Department of Mathematics, Physics and Electrical Engineering, Northumbria University, Newcastle upon Tyne, United Kingdom
14. Genómica del Cáncer, Instituto Nacional de Medicina Genómica, Mexico City, 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 numbers 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 PM_2.5, 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: PM_2.5, 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 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 declines in August. Regarding hypertensive diseases, only PM_2.5 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 PM_2.5, 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.