Elsevier

Environmental Research

Volume 176, September 2019, 108545
Environmental Research

Review article
Impact of ambient air pollution on physical activity and sedentary behavior in China: A systematic review

https://doi.org/10.1016/j.envres.2019.108545Get rights and content

Abstract

This study systematically reviewed scientific evidence linking ambient air pollution to physical activity and sedentary behavior in China. A keyword and reference search was conducted in PubMed, Web of Science, and the Cochrane Library. Predetermined selection criteria included—study designs: interventions or experiments, retrospective or prospective cohort studies, cross-sectional studies, and case-control studies; subjects: people of all ages; exposures: specific air pollutants and/or overall air quality; outcomes: physical activity and/or sedentary behavior; and country/area: mainland China. Ten studies met the selection criteria and were included in the review. Six adopted a cross-sectional design and the remaining four adopted a prospective cohort design. Four studies assessed a specific air pollutant namely particulate matter with diameter <2.5 μg/m3 (PM2.5), whereas the remaining six focused on overall air quality, defined using air quality indexes. Decline in overall air quality and increase in PM2.5 concentration were found to be associated with reduced daily/weekly duration of outdoor leisure-time and/or transportation-related physical activity such as walking but increased duration of daytime/nighttime sleeping among Chinese residents. In contrast, evidence linking overall air quality and PM2.5 concentration to sedentary behavior remains mixed and inconclusive. In conclusion, preliminary evidence indicates that ambient air pollution impacts Chinese residents’ daily physical activity-related behaviors. Future studies adopting objective measures of physical activity and a longitudinal or experimental study design are warranted to examine the impact of air pollution on sensitive sub-populations such as children, older adults and people with pre-existing conditions, and in locations outside China.

Introduction

Although the adverse effects of ambient or outdoor air pollution on health have been extensively documented (World Health Orginaization, 2018), much less is known regarding its impact on local residents’ health behaviors, including physical activity, sedentary behavior, and sleeping. Increasing numbers of children and adults in both high-income and low- and middle-income countries (LMICs) fall short of the guidelines-recommended physical activity levels (Li, 2016; Muntner et al., 2005). Physical inactivity is a leading risk factor for morbidity and mortality worldwide (Arsenault et al., 2010; Kruk, 2014; Lee et al., 2012). Sedentary behavior refers to any waking behavior characterized by low energy expenditure while in a sitting, reclining or lying posture; long sedentary time has been found to adversely impact cardio-metabolic health (van der Ploeg and Hillsdon, 2017). The risk of all-cause and cardiovascular mortality significantly increases when total sedentary time is longer than 6–8 h a day and/or total television watching time is longer than 3–4 h a day (Patterson et al., 2018). More time spent outdoors is positively associated with moderate-to-vigorous intensity physical activity, helps people meet the guidelines-recommended physical activity level, and improves cardiorespiratory fitness (Schaefer et al., 2014).

Ambient air pollution may discourage people from engaging in regular outdoor physical activity through several mechanisms. First, exposure to air pollution is linked to decreased lung function, elevated blood pressure, and other cardiovascular and respiratory symptoms (Auchincloss et al., 2008; Brook et al., 2010; Cakmak et al., 2011), resulting in impaired exercise capacity and performance (Cutrufello et al., 2011; Marr and Ely, 2010; Rundell and Caviston, 2008). Second, smog appearance may discourage people from engaging in outdoor activities (Roberts et al., 2014). Finally, media alerts and warnings of poor air quality may alter people’s decision on spending time outdoors and engaging in physical activity (Saberian et al., 2017; Wen et al., 2009a). For example, the Canadian government developed a risk communication tool, the Air Quality Health Index (AQHI), which uses a 10-point scale from low to high risk to deliver information regarding the health implications of air pollution to the general public (Government of Canada, 2015). In high air pollution days, the AQHI recommends to “reduce or reschedule strenuous activities outdoors” in order to mitigate the health risks of air pollution (Government of Canada, 2017).

A previous review systematically identified and synthesized scientific literature that examined the impact of air pollution on physical activity (An et al., 2018). Among the seven studies included in the review (An et al., 2018), six were conducted in the U.S. and one in the U.K. All U.S.-based studies adopted a cross-sectional study design (An and Xiang, 2015; Hankey et al., 2012; Roberts et al., 2014; Wells et al., 2012; Wen et al. 2009a, 2009b), and the U.K.-based study adopted a prospective cohort design (Alahmari et al., 2015). Specific air pollutants assessed included particulate matter with diameter <2.5 μg/m3 (PM2.5), particulate matter with diameter < 10 μg/m3 (PM10), ozone (O3), and nitrogen oxides (NOx), whereas two studies focused on overall air quality (i.e., air quality index [AQI]). All studies found that air pollution was negatively associated with physical activity and positively associated with leisure-time physical inactivity. Study participants, in particular those with respiratory disease, reported a reduction in outdoor activities in order to mitigate the detrimental impact of air pollution. The meta-analysis based on cross-sectional studies found that one unit (μg/m3) increase in ambient PM2.5 concentration was associated with a 10% increase in the odds of physical inactivity among U.S. adults. Air pollution was measured by fixed monitoring stations (Hankey et al., 2012; Roberts et al., 2014; Wen et al., 2009b) or personal sensors (Alahmari et al., 2015). Five studies focused on the impact of air pollution concentration on health behaviors (Alahmari et al., 2015; An and Xiang, 2015; Hankey et al., 2012; Roberts et al., 2014; Wen et al., 2009b), whereas the other two focused on the communication about air pollution in relation to health behaviors (Wells et al., 2012; Wen et al., 2009a). In particular, Wen et al. (2009a) reported that media air pollution alerts via radio, television, and newspaper were associated with reduced outdoor physical activity among local residents. Wells et al. (2012) reported that self-perceived air quality and air quality information communicated by local media were associated with changes in physical activity level among people with respiratory diseases. The review identified a few important limitations in the existing literature, including lack of large-scale longitudinal studies, self-reported physical activity levels that were prone to measurement error and social desirability bias, and lack of studies located in the LMICs.

It should be noted that the relationship between air pollution and physical activity may be nonlinear, and air pollution could impact physical activity behavior only after passing certain threshold concentration. In the U.S., most counties have already met the national air quality standards of PM2.5 concentration levels, with fewer than 10 out of >3,000 counties in the U.S. not meeting the national standard of 12.0 μg/m3 (on annual mean concentration) by 2020 (Environmental Protection Agency, 2012). In sharp contrast, 365 out of the 366 major cities in China exceeded the PM2.5 standard of 12 μg/m3 in 2016 (Clean Air Asia, 2016). The 100 most polluted cities (including many of the largest cities such as Beijing, Tianjin, and Chengdu) had annual average PM2.5 concentration levels seven to 19 times as high as the U.S. national average (8.5 μg/m3) in 2015 (Clean Air Asia, 2016). Air pollution is estimated to cause 1.6 million deaths per year in China, roughly 17% of all deaths nationwide (Rohde and Muller, 2015). Thus, results from studies based in the U.S. and U.K. may not pertain to the high pollution settings in China (An et al., 2018). In a commentary article, Li et al. (2015) speculated that the threat of the health damage of PM2.5 air pollution could impact the implementation of China’s physical activity programs (Li et al., 2015). In particular, Li et al. (2015) posits that severe ambient air pollution (e.g., AQI ≥ 300) may require cancellation of physical education classes or sport activities for school children (Li et al., 2015). Furthermore, both the actual air pollution level and the communication around it might impede older Chinese adults from engaging in popular outdoor activities such as walking and dancing.

This study aimed to systematically identify and review literature regarding the impact of outdoor air pollution on physical activity-related behaviors in China. It also aimed to identify the limitations and gaps in this field to guide future research.

Section snippets

Study selection criteria

Studies that met all of the following criteria were included in the review: (1) Study designs: interventions or experiments, retrospective or prospective cohort studies, cross-sectional studies, and case-control studies; (2) Subjects: people of all ages (3) Exposures: specific air pollutants (e.g., PM10, PM2.5, O3, and NOx); and overall air quality; (4) Outcomes: physical activity, sedentary behavior, and sleeping; (5) country/area: mainland China; (6) Article type: peer-reviewed publications;

Study selection

Fig. 1 shows the study selection flowchart. We identified a total of 14 183 articles through keyword and reference search, including 5 716 articles from PubMed, 8 242 articles from Web of Science, 224 articles from the Cochrane Library, and one article from Google Scholar through hand-searching. After removing duplicates, 13 013 articles underwent title and abstract screening, in which 12 996 articles were excluded. The remaining 17 articles were reviewed in full text against the study

Discussion

This study systematically reviewed scientific evidence linking ambient air pollution to physical activity-related behavior modifications in China. A total of 10 studies were identified. Six used a cross-sectional design and the remaining four used a prospective cohort design. Four studies assessed a specific air pollutant namely PM2.5, whereas the remaining six focused on overall air quality using AQI. Decline in overall air quality and increase in PM2.5 concentration were found to be

Conclusion

This study systematically reviewed scientific evidence regarding the influence of ambient air pollution on physical activity-related behaviors in China. Ten studies met the selection criteria and were included in the review. Decline in overall air quality and increase in PM2.5 concentration were found to be associated with reduced daily/weekly duration of outdoor leisure-time and/or transportation-related physical activity such as walking, running and biking but increased duration of

Compliance with ethical standards

This study is non-human subject research and is exempt from ethical approval by the corresponding author’s university.

Conflicts of interest

The authors have no conflict of interests to declare.

Funding

The study was partially funded by Guangzhou Sport University. The funder has no role in the design, execution, interpretation, or writing of the study.

References (47)

  • M. Yang et al.

    Potential for revival of the bicycle in Beijing

    Int. J. Sustain. Transport.

    (2016)
  • H. Yu et al.

    The association between ambient fine particulate air pollution and physical activity: A cohort study of university students living in Beijing

    Int. J. Behav. Nutr. Phys. Act.

    (2017)
  • P. Zhao et al.

    How does air pollution influence cycling behaviour? Evidence from Beijing

    Transport. Res. Transport Environ.

    (2018)
  • A.D. Alahmari et al.

    Influence of weather and atmospheric pollution on physical activity in patients with COPD

    Respir. Res.

    (2015)
  • R. An et al.

    Impact of ambient air pollution on physical activity among adults: A systematic review and meta-analysis

    Perspect. Public Health

    (2018)
  • B. Arsenault et al.

    Physical inactivity, abdominal obesity and risk of coronary heart disease in apparently healthy men and women

    Int. J. Obes.

    (2010)
  • A.H. Auchincloss et al.

    Associations between recent exposure to ambient fine particulate matter and blood pressure in the Multi-Ethnic Study of Atherosclerosis (MESA)

    Environ. Health Perspect.

    (2008)
  • M. Braniš et al.

    PM10, ambient temperature and relative humidity during the XXIX Summer Olympic Games in Beijing: Were the athletes at risk

    Aerosol Air Qual. Res.

    (2010)
  • R.D. Brook et al.

    Particulate matter air pollution and cardiovascular disease: An update to the scientific statement from the American Heart Association

    Circulation

    (2010)
  • China Air 2016:Air Pollution Prevention and Control Progress in Chinese Cities

    (2016)
  • P.T. Cutrufello et al.

    Inhaled whole exhaust and its effect on exercise performance and vascular function

    Inhal. Toxicol.

    (2011)
  • T.H. de Sá et al.

    Health Impact Modelling of Different Travel Patterns on Physical Activity, Air Pollution and Road Injuries for São Paulo, Brazil

    (2017)
  • C. Di Novi

    The influence of traffic‐related pollution on individuals' life‐style: Results from the BRFSS

    Health Econ.

    (2010)
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