Previous studies suggest that air pollution has a negative effect on semen quality. However, most studies are cross-sectional and the results are controversial. This study investigated the associations between air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, CO, and O₃) and semen quality among sperm donation candidates, especially when the air pollution was artificially controlled in Beijing, China. We analyzed 8945 semen samples in the human sperm bank of Peking University Third Hospital (Beijing, China) from October 2015 to May 2018. Air pollution data during the entire period (0-90 days prior) and key stages (0-9, 10-14, and 70-90 days prior) of sperm development were collected from the China National Environmental Monitoring Centre. The association between air pollutants and semen parameters (sperm concentration and progressive motility) was analyzed by a mixed model adjusted for age, abstinence duration, month, and average ambient temperature. Only O₃during key stages of 0-9 days and 10-14 days and the entire period was negatively associated with sperm concentration between 2015 and 2018 (P < 0.01). During the period of air pollution control from November 2017 to January 2018, except for the increase in O₃concentration, other five pollutants' concentrations decreased compared to those in previous years. In this period, the sperm concentration decreased (P < 0.001). During the pollution-control period, O₃exposure 10-14 days prior was negatively associated with sperm concentration (95% CI: -0.399--0.111; P < 0.001). No significant association was found between the other five pollutants and semen quality during that period. Our study suggested that only O₃exposure was harmful to semen quality. Therefore, O₃should not be neglected during pollution control operation.
Adolescent ; Adult ; Air Pollutants/analysis* ; Air Pollution/adverse effects* ; Beijing ; Cross-Sectional Studies ; Environmental Monitoring ; Humans ; Longitudinal Studies ; Middle Aged ; Oxidants, Photochemical/adverse effects* ; Ozone/adverse effects* ; Particulate Matter/analysis* ; Semen Analysis ; Sperm Count ; Sperm Motility ; Young Adult

OBJECTIVETo investigate whether photochemical smog emitted during the process of electric arc welding might cause oxidative stress and potential oxidative damage in the bodies of welding operators.

METHODSSeventy electric arc welding operators (WOs) and 70 healthy volunteers (HVs) were enrolled in a randomized controlled study design, in which the levels of vitamin C (VC) and vitamin E (VE) in plasma as well as the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and the level of lipoperoxide (LPO) in erythrocytes were determined by spectrophotometry.

RESULTSCompared with the average values of the above experimental parameters in the HVs group, the average values of VC and VE in plasma as well as those of SOD, CAT and GPX in erythrocytes in the WOs group were significantly decreased (P < 0.005-0.0001), while the average value of LPO in erythrocytes in the WOs group was significantly increased (P < 0.0001). The findings from the partial correlation analysis on the controlling of age suggested that with a prolonged duration of exposure to photochemical smog the values of VC, VE, SOD, and GPX, except for CAT, in the WOs were decreased gradually (P < 0.05-0.005), the value of LPO in the WOs was increased gradually (P < 0.001), and that with the ozone dose increased in the air in each worksite VC, VE, SOD, CAT and GPX decreased (P < 0.005-0.001), but LPO increased (P < 0.001). The findings from the reliability analysis for the VC, VE, SOD, CAT, GPX, and LPO values which were used to reflect oxidative stress and potential oxidative damage in the WOs showed that the reliability coefficients' alpha (6 items) was 0.8021, P < 0.0001, and that the standardized item alpha was 0.9577, P < 0.0001.

CONCLUSIONFindings in the present study suggest that there exists an oxidative stress induced by long-term exposure to photochemical smog in the bodies of WOs, thereby causing potential oxidative and lipoperoxidative damages in their bodies.

Adult ; Antioxidants ; metabolism ; Ascorbic Acid ; blood ; Catalase ; blood ; Erythrocytes ; metabolism ; Glutathione Peroxidase ; blood ; Humans ; Lipid Peroxides ; blood ; Middle Aged ; Nitric Oxide ; blood ; Oxidants, Photochemical ; adverse effects ; analysis ; Oxidative Stress ; Ozone ; analysis ; toxicity ; Risk Assessment ; Smog ; Superoxide Dismutase ; blood ; Vitamin E ; blood ; Welding