Seasonal variation in health effects of particulate matter in Tianjin

BackgroundAdverse health effects associated with particulate matter have been demonstrated, but findings on seasonal variation in the health impacts are inconsistent. ObjectiveTo explore potential seasonal variation in particulate matter (PM2.5 and PM10) associated daily non-accidental mortality and corresponding years of life loss (YLL) in Tianjin. MethodsThe daily data of non-accidental deaths, air pollution, and meteorological factors in Tianjin from 2014 to 2019 were collected. A generalized additive model, with adjusting selected confounding factors such as temperature, relative humidity, long-term trends, day of the week, and holiday, was used to quantitatively evaluate the relationships of PM2.5 and PM10 with daily non-accidental deaths and YLL. ResultsThe effects of PM2.5 and PM10 on daily non-accidental mortality and corresponding YLL were statistically significant in full year, spring, summer, and autumn (except for the effect of PM10 on non-accidental YLL in spring), but not statistically significant in winter. The non-accidental mortality and it's 95%CI increased by 0.28% (0.11%-0.44%) and 0.24% (0.11%-0.36%) in full year, 0.44% (0.11%-0.77%) and 0.17% (0.00%-0.33%) in spring, 1.32% (0.50%-2.16%) and 2.15% (1.54%-2.76%) in summer, and 0.68% (0.30%-1.06%) and 0.57% (0.28%-0.87%) in autumn for every 10 µg·m−3 increase in PM2.5 and PM10 concentrations, respectively; the corresponding YLL and it's 95%CI increased by 7.41 (2.42-13.07) and 5.75 (1.94-9.57), 13.11 (3.00-23.22) and 2.88 (−2.82-8.59), 34.66 (11.92-57.40) and 48.12 (31.48-64.75), and 16.13 (4.57-27.70) and 12.60 (3.56-21.65) person-years, respectively. When adopting the limits in the Global Air Quality Guidelines (2021) as the reference, excess deaths and YLL caused by PM2.5 and PM10 exposure were the greatest in summer. The excess deaths and it's 95%CI were 5.38 (5.08-5.69) and 8.62 (7.95-9.28), and the excess YLL and it's 95%CI were 112.23 (105.79-118.67) and 156.94 (44.99-168.89) person-years, respectively. ConclusionThe effects of particulate matter on non-accidental mortality and corresponding YLL may vary seasonally in Tianjin with the greatest effects in summer, suggesting that the health protection related to particulate matter should be strengthened in summer.