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Air pollution is a widespread problem that affects all areas of society because poor air quality results in an increase in the incidence of various diseases that are influenced by the environment, notable among which are kidney diseases. Studies indicate that prolonged exposure to moderate-to-high concentrations of particulate matter (PM) can decrease renal function, promoting the progression of chronic kidney diseases and related problems. Despite emission controls on the road transport sector, people of the Metropolitan Area of São Paulo (MASP) have been exposed to air pollutants concentrations above the WMO guidelines for many years, especially surface ozone and fine particles. Therefore, the objective of this study was to explore the impact of air pollution on glomerular and chronic kidney diseases in the city of São Paulo, Brazil, through the use of statistical models.
Meteorological and air quality data were obtained from monitoring stations operated by the São Paulo State Environmental Protection Agency. The variables analyzed included average daily temperatures, relative humidity (%), PM < 2.5 µm (PM2.5) concentration, and daily hospital admissions in São Paulo City during the 2011–2021 period. Hospitalization records were extracted from the public health care system and from private facilities affiliated with the public health care system. The patients investigated were diagnosed with diseases directly or indirectly linked to kidney problems, as defined in the International Classification of Diseases, 10th revision. Daily hospitalization admissions were categorized by patient age and sex. Regression analysis, employing the Generalized Additive Model in conjunction with negative binomial distribution of exponential probability, was performed in a time series. We examined temperature, relative humidity, and PM2.5 concentrations for each group. Two other variables - holiday and weekday data - were introduced into the model. Given the nonlinearity of the effects of exposure to PM, we assessed the cumulative impact of exposure in the medium term. We also employed the distributed lag non-linear models, which provides a modeling framework that simultaneously considers the response to exposure and the effects of time lags. The lag considered was up to 2,000 days (approximately 5 years) for all groups, (PM Kidney Consortium, FAPESP, NWO).
These preliminary results show that the risks of exposure to air pollution are most clearly defined (relative risk, 1.04; 95% CI:1.02-1.05) in adult women (18 < age > 60 years), which could be attributed to hormonal or physiological factors. For younger women, the risk is not yet established, whereas the risk in older women became evident after ≥ 5 years of exposure. For almost all groups, exposure to PM2.5 concentrations > 10 µg/m³ for a prolonged period (more than 2,000 days) was found to increase the risk of developing one of the diseases analyzed. Men, especially older men, tended to be more susceptible (relative risk ≤ 1.05; 95% CI: 1.01-1.06).
In conclusion, exposure to air pollution seems to increase the incidence of glomerular and chronic kidney disease.