Association between air pollution and emergency room admission for eye diseases in Rome, Italy: A time-series analysis

Abstract

Eye diseases impose a significant burden on health services due to high case numbers. However, exposure to outdoor air pollution is seldom mentioned as potential harmful factor. We conducted a time-series analysis in Rome, Italy, to estimate the association between daily mean concentration of NO2, PM10 and PM2.5 and daily number of emergency room (ER) admissions for a selected cluster of eye diseases from 2006 to 2016. We used Poisson regression adjusted for time trend, population decrease during summer vacations and holidays, day of week, apparent temperature (hot and cold) and daily concentration of nine pollen species. We observed 581,868 ER admissions during the study period. 44.74% of cases were observed in subjects with less than 20 years, 19.50% in 51–65 age category and 13.4% among children (0–14 years). No differences between sexes were recorded.Mean values of pollutant concentrations were 54.75, 31.01 and 18.14 μg/m3 for NO2, PM10 and PM2.5 respectively. The air temperature ranged from −1 °C to 32.5 °C, with a mean value of 16 °C (SD = 6.88). The apparent temperature spaced from −3.58 °C to 34.08 °C (mean = 15.61 °C, SD = 8.5).The highest percent risk increases for 10 μg/m3 increases of the three pollutants were observed at lag0-1 day (1.3%, 0.63–1.98 for PM2.5; 1.03%, 0.56–1.51 for PM10 and 0.6%, 0.13–1.07 for NO2). Risk increased significantly also at lag0 and lag0-5 day for each pollutant. Secondary analyses showed higher effects in the elderly compared to younger subjects. No differences emerged between sexes. The dose response analysis suggested of possible effects on ER admission risk also at low-level concentrations of PM2.5. A strong confounding effect of pollen was not detected. Resultsof this study are coherent with previous analyses. Speculation can be done about the biological mechanisms that link air pollution to eye damage.