Ambient ozone exposure combined with residential greenness in relation to serum sex hormone levels in Chinese rural adults

Long-term exposure to ambient ozone (O3) and residential greenness independently relate to altered hormones levels in urban settings and developed countries. However, independent and their joint associations with progestogen and androgen were sparsely studied in rural regions.A total of 6211 individuals were recruited in this study. Random forest model was applied to predict the daily average concentrations of O3 using the satellites data. Residential greenness was reflected by the normalized difference vegetation index (NDVI). Liquid chromatography-tandem mass spectrometry was used to measure serum progestogen and androgen concentrations. Gender and menopausal status modified associations of long-term exposure to O3 and residential greenness with hormones levels were analyzed by generalized linear models.Long-term exposure to O3 was negatively related to 17-hydroxyprogesterone, testosterone, and androstenedione in both men and women (premenopausal and postmenopausal); the estimated β and 95% CI of ln-progesterone in response to per 10 μg/m3 increment in O3 concentration was -0.560 (-0.965, -0.155) in postmenopausal women. Association of long-term exposure to O3 with serum androgen levels in premenopausal and postmenopausal women were alleviated by residing in places with higher greenness. Additionally, a prominent effect of long-term exposure to O3 related to decreased serum progestogen and androgen levels was found in participants with middle- or high-level of physical activity or lower education level.The results suggested that long-term exposure to high levels of O3 related to decreased serum androgen levels was attenuated by living in high greenness places in women regardless of menopause status. Future studies are needed to confirm the positive health effects of residential greenness on the potential detrimental effects due to exposure to O3.