Associations of long-term nitrogen dioxide exposure with a wide spectrum of diseases: a prospective cohort study of 0·5 million Chinese adults
Xi Xia, Xia Meng, Cong Liu, Yi Guo, Xinyue Li, Yue Niu, Hubert Lam, Neil Wright, Christiana Kartsonaki, Yiping Chen, Ling Yang, Huaidong Du, Canqing Yu, Dianjianyi Sun, Jun Lv, Junshi Chen, Xiaoming Yang, Ruqin Gao, Shaowei Wu, Haidong Kan, Ka Hung Chan, Liming Li, Zhengming Chen, Liming Li, Zhengming Chen, Junshi Chen, Zhengming Chen, Robert Clarke, Rory Collins, Liming Li, Jun Lv, Richard Peto, Robin Walters, Ahmed EdrisMohamed, Alfred Pozarickij, Andri Iona, Baihan Wang, Charlotte Clarke, Christiana Kartsonaki, Dan Schmidt, Daniel Avery, Derrick Bennett, Hannah Fry, Huaidong Du, Hubert Lam, Iain Turnbull, Iona Millwood, James Liu, Jonathan Clarke, Ka Hung Chan, Ka Hung Chan, Kshitij Kolhe, Kuang Lin, Lin Wang, Ling Yang, Maria Kakkoura, Maryam Rahmati, Maxim Barnard, Mohsen Mazidi, Neil Wright, Pang Yao, Paul Ryder, Pek Kei Im, Prapthi Harish, Qunhua Nie, Rebecca Stevens, Robert Clarke, Robin Walters, Ruth Boxall, Sam Morris, Simon Gilbert, Xiaoming Yang, Yiping Chen, Zhengming Chen, Xiao Han, Can Hou, Qingmei Xia, Chao Liu, Jun Lv, Pei Pei, Dianjianyi Sun, Canqing Yu, Lang Pan, Zengchang Pang, Ruiqin Gao, Shanpeng Li, Haiping Duan, Shaojie Wang, Yongmei Liu, Ranran Du, Yajing Zang, Liang Cheng, Xiaocao Tian, Hua Zhang, Yaoming Zhai, Feng Ning, Xiaohui Sun, Feifei Li, Silu Lv, Junzheng Wang
Abstract
Background Little evidence is available on the long-term health effects of nitrogen dioxide (NO 2 ) in low-income and middle-income populations. We investigated the associations of long-term NO 2 exposure with the incidence of a wide spectrum of disease outcomes, based on data from the China Kadoorie Biobank. Methods This prospective cohort study involved 512 724 Chinese adults aged 30–79 years recruited from ten areas of China during 2004–08. Time-varying Cox regression models yielded adjusted hazard ratios (HRs) for the associations of long-term NO 2 exposure with aggregated disease incidence endpoints classified by 14 ICD-10 chapters, and incidences of 12 specific diseases selected from three key ICD-10 chapters (cardiovascular, respiratory, and musculoskeletal diseases) found to be robustly associated with NO 2 in the analyses of aggregated endpoints. All models were stratified by age-at-risk (in 1-year scale), study area, and sex, and were adjusted for education, household income, smoking status, alcohol intake, cooking fuel type, heating fuel type, self-reported health status, BMI, physical activity level, temperature, and relative humidity. Findings The analysis of 512 709 participants (mean baseline age 52·0 years [SD 10·7]; 59·0% female and 41·0% male) included approximately 6·5 million person-years of follow-up. Between 5285 and 144 852 incident events were recorded for each of the 14 aggregated endpoints. Each 10 μg/m 3 higher annual average NO 2 exposure was associated with higher risks of chapter-specific endpoints, especially cardiovascular (n=144 852; HR 1·04 [95% CI 1·02–1·05]), respiratory (n=73 232; 1·03 [1·01–1·05]), musculoskeletal (n=54 409; 1·11 [1·09–1·14]), and mental and behavioural (n=5361; 1·12 [1·05–1·21]) disorders. Further in-depth analyses on specific diseases found significant positive supra-linear associations with hypertensive disease (1·08 [1·05–1·11]), lower respiratory tract infection (1·03 [1·01–1·06]), arthrosis (1·15 [1·09–1·21]), intervertebral disc disorders (1·13 [1·09–1·17]), and spondylopathies (1·05 [1·01–1·10]), and linear associations with ischaemic heart disease (1·03 [1·00–1·05]), ischaemic stroke (1·08 [1·06–1·11]), and asthma (1·15 [1·04–1·27]), whereas intracerebral haemorrhage (1·00 [0·95–1·06]), other cerebrovascular disease (0·98 [0·96–1·01]), acute upper respiratory infection (1·03 [0·96–1·09]), and chronic lower respiratory disease (0·98 [0·95–1·02]) showed no significant association. NO 2 exposure showed robust null association with external causes (n=32 907; 0·98 [0·95–1·02]) as a negative control. Interpretation In China, long-term NO 2 exposure was associated with a range of diseases, particularly cardiovascular, respiratory, and musculoskeletal diseases. These associations underscore the pressing need to implement the recently tightened WHO air quality guidelines. Funding Wellcome Trust, UK Medical Research Council, Cancer Research UK, British Heart Foundation, National Natural Science Foundation of China, National Key Research and Development Program of China, Sino-British Fellowship Trust, and Kadoorie Charitable Foundation.