Associação entre internações por síndrome respiratória aguda grave (SRAG) e variáveis ambientais na Baixada Santista, 2015-2024

Abstract

Acute respiratory infections, particularly when they progress to Severe Acute Respiratory Infection (SARI), represent an important public health problem because of their impact on morbidity, mortality, and the demand for hospital care. In the Baixada Santista region, characteristics such as high population density, a humid tropical climate, intense vehicular traffic, and port and industrial activities may influence the occurrence and worsening of respiratory conditions. This study aimed to analyze the association between SARI cases and concentrations of inhalable particulate matter (PM10), fine particulate matter (PM2.5), air temperature, and relative humidity in the nine municipalities of the Baixada Santista region from 2015 to 2024. This was a longitudinal ecological study with a quantitative approach, based on secondary epidemiological data and environmental information obtained from the QUALAR system of the São Paulo State Environmental Company. A total of 33,616 SARI records were analyzed according to municipality of residence, age group, sex, race/skin color, and temporal distribution. The analyses included descriptive statistics, time-series analysis, and regression models for count data, with assessment of cumulative and lagged effects from zero to seven days. Santos accounted for the largest number of records, followed by São Vicente, Guarujá, and Praia Grande. Individuals aged 60 years or older represented 26.6% of the cases, followed by those aged 36 to 60 years, with 20.5%, and children aged 1 to 4 years, with 18.7%. The environmental analysis showed a nonlinear association between the exposures and the occurrence of SARI. For PM10, a concentration of 100 μg/m³ was associated with a cumulative relative risk of 1.044, with a 95% confidence interval of 1.011 to 1.079, indicating a 4.4% increase in risk compared with the reference value. For PM2.5, the association became statistically significant from 15 μg/m³ onward, with a relative risk of 1.025 and a 95% confidence interval of 1.002 to 1.049. Higher concentrations of both pollutants were associated with a progressive increase in relative risk. Air temperatures above 30 °C were also associated with an increased occurrence of SARI, particularly at temperatures of 35 °C or higher. Relative humidity showed a nonlinear pattern, with statistically significant associations at approximately 70% and 80%, whereas, for most of the lag periods analyzed, the confidence intervals included the null value. It was concluded that higher concentrations of PM10 and PM2.5 and higher air temperatures were associated with an increased risk of SARI, although the magnitude and temporal distribution of the effects varied across exposures. Integrated monitoring of epidemiological indicators, air quality, and meteorological conditions may contribute to the planning of preventive actions, the organization of healthcare services, and the development of environmental health policies in the Baixada Santista region.