| dc.description.abstract | Abstract
Introduction: Although there is evidence regarding PMs associations, particularly PM2.5, with cardiorespiratory morbidity and mortality; more studies are needed to understand the biological mechanisms underlying these associations. We examined the effects of short-term exposure to PM2.5 on biomarkers of airway inflammation, oxidative stress, and gene expression related to respiratory diseases among healthy adolescents in a highly polluted urban area (TBZ), compared to a less polluted city (HDS).
Methods: This panel study was conducted from November 2019 to February 2020. The survey was initiated using a baseline questionnaire to collect the student’s health and general information in each geographic area (1109 subjects in TBZ and 350 subjects in HDS). Based on the inclusion criteria, the eligible individuals were recruited through the questionnaire and the physician examination. We enrolled and followed a panel of 97 healthy nonsmoking participants living in two different cities (TBZ and HDS). For five consecutive months, the subjects were examined and biological samples were obtained. Selected markers include: hemodynamic markers, FENO, and EBC biomarkers (IL-6, TNF-α, NOx, Nrf2). We measured daily outdoor PM2.5 mass concentration in a fixed station in each location starting 6 days before each biological sampling day. The PM-metal content was analyzed by ICP-MS. The linear mixed-effects regression models were applied for data analysis.
Results: Of the 1,459 subjects aged 15-18 years, according to the ISAAC questionnaire, the prevalence of asthma were 13.4 % and 8.3 % in TBZ and HDS, respectively. The averages of PM2.5 mass and total metals in the fall in TBZ were 34.36 µg/m3 and 320.99 ng/m3 that nearly two and six times higher than in HDS, respectively. In TBZ, an increased IQR of PM2.5 mass during 0-5 days was associated with a significant rise in diastolic blood pressure [10.47 % (3.94, 17.01)], heart rate [10.47 % (4.58, 16.36)], TNF-α [38.73 % (17.62, 63.64)], FENO [53.51 % (3.50, 98.68)], NOx [12.91% (2.29, 24.63)], and Nrf2 [20.09 % (6.08 , 35.96)] but a reduction in systolic blood pressure [2.07 % (-4.06, -0.08)] and IL-6 [32.46 % (-54.09, -8.83)]. Moreover, exposure to low PM2.5 concentration is significantly associated with an elevation in diastolic blood pressure in HDS [2.73 % (0.83, 4.63)]. We also observed that exposure to metal constituents in highly polluted region is associated with increased TNF-α and IL-6 with 131.80% (95% CI: 56.01, 244.39) and 47.51% (95% CI: 33.01, 62.05) per IQR of Hg, respectively.
Conclusion: This study shows that exposure to ambient PM2.5 in a highly polluted areas may incite significant changes in airway inflammation and oxidative stress markers as well as related gene expression. Also exposure to low levels of PM2.5 in the less polluted region, might trigger blood pressure and airway oxidative stress markers in healthy individuals. | en_US |
