Long-term exposure to PM2.5 and Children's lung function: a dose-based association analysis

Sai Li; Suzhen Cao; Xiaoli Duan; Yaqun Zhang; Jicheng Gong; Xiangyu Xu; Qian Guo; Xin Meng; Mcswain Bertrand; Junfeng Jim Zhang

doi:10.21037/jtd-19-crh-aq-007

Long-term exposure to PM2.5 and Children's lung function: a dose-based association analysis

J Thorac Dis. 2020 Oct;12(10):6379-6395. doi: 10.21037/jtd-19-crh-aq-007.

Authors

Sai Li¹, Suzhen Cao¹, Xiaoli Duan¹, Yaqun Zhang², Jicheng Gong³, Xiangyu Xu¹, Qian Guo¹, Xin Meng³, Mcswain Bertrand¹, Junfeng Jim Zhang^{3

4

5

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Affiliations

¹ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, China.
² Gansu Provincial Design and Research Institute of Environmental Science, Lanzhou, China.
³ Beijing Innovation Center for Engineering Science and Advanced Technology, State Key Joint Laboratory for Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, And Center for Environment and Health, Peking University, Beijing, China.
⁴ Duke Kunshan University, Kunshan, China.
⁵ Nicholas School of the Environment and Duke Global Health Institute, Duke University, Durham, USA.
⁶ Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China.

Abstract

Background: The current literature is still not consist regarding the effect of long-term exposure to PM2.5 and children's lung function, partly due to inadequate or inaccurate exposure assessment. In this study, we aim to investigate the associations between long-term exposure to PM2.5, estimated as average daily dose (ADD), and lung function in school-age children.

Methods: We recruited 684 participants of 7-12 years old from the city of Lanzhou located in northwestern China. Participants underwent spirometric tests for lung function and responded to a questionnaire survey. Detailed information about individual air exposure and personal information were collected, including length of school hours, home address, age, gender, etc. Combining the spatial distribution of PM2.5 concentrations in the past 5 years and individual time-activity data, we estimated annual ADD for 5 years preceding the lung function tests and 5-year average ADD, respectively. We used multiple linear regression models to examine the associations between ADD values and lung function, controlling for a range of individual-level covariates.

Results: The 5-year average ADD among all the participants was 50.5 µg/kg-d, with higher values estimated for children living in the urban area than the suburban area, for boys than girls, and for children whose parents received a lower education attainment. We found that a 1 μg/kg-d increment in ADD of PM2.5 was associated with a 10.49 mL (95% CI: -20.47, -0.50) decrease in forced vital capacity (FVC) and a 7.68 mL (95% CI: -15.80, -0.44) decrease in forced exploratory volume in 1 second (FEV₁). Among the annual ADDs estimated for the preceding 5 years, the immediate past year prior to lung function measurement had the greatest effect on lung function. The effect was greater in girls than in boys. We found no associations between annual exposure of PM2.5 (instead of ADD) and lung function when defined concentration was used as an exposure variable.

Conclusions: Long-term PM2.5 exposure, when estimated as exposure dose averaged over a year or longer, was associated with statistically significant reductions in FVC and FEV1 in children of elementary-school age. Future studies may consider the use of individual-level dose estimates (as opposed to exposure concentrations) to improve the dose-response assessment.

Keywords: Children; average daily dose (ADD); fine particulate matter (fine PM); lung function.