Elsevier

Environment International

Volume 94, September 2016, Pages 76-82
Environment International

Full length article
Short-term exposure to high ambient air pollution increases airway inflammation and respiratory symptoms in chronic obstructive pulmonary disease patients in Beijing, China

https://doi.org/10.1016/j.envint.2016.05.004Get rights and content

Highlights

  • Few studies have investigated air pollution effects in COPD patients in China.

  • Air pollution was associated with increased exhaled nitric oxide and hydrogen sulfide.

  • Air pollution was also associated with increased odds ratios of respiratory symptoms.

  • Exhaled hydrogen sulfide may serve as a novel marker to detect air pollution effects.

  • Air pollution may pose risk to respiratory health in highly-polluted areas.

Abstract

Background

Few studies have investigated the short-term respiratory effects of ambient air pollution in chronic obstructive pulmonary disease (COPD) patients in the context of high pollution levels in Asian cities.

Methods

A panel of 23 stable COPD patients was repeatedly measured for biomarkers of airway inflammation including exhaled nitric oxide (FeNO) and exhaled hydrogen sulfide (FeH2S) (215 measurements) and recorded for daily respiratory symptoms (794 person-days) in two study periods in Beijing, China in January–September 2014. Daily ambient air pollution data were obtained from nearby central air-monitoring stations. Mixed-effects models were used to estimate the associations between exposures and health measurements with adjustment for potential confounders including temperature and relative humidity.

Results

Increasing levels of air pollutants were associated with significant increases in both FeNO and FeH2S. Interquartile range (IQR) increases in PM2.5 (76.5 μg/m3, 5-day), PM10 (75.0 μg/m3, 5-day) and SO2 (45.7 μg/m3, 6-day) were associated with maximum increases in FeNO of 13.6% (95% CI: 4.8%, 23.2%), 9.2% (95% CI: 2.1%, 16.8%) and 34.2% (95% CI: 17.3%, 53.4%), respectively; and the same IQR increases in PM2.5 (6-day), PM10 (6-day) and SO2 (7-day) were associated with maximum increases in FeH2S of 11.4% (95% CI: 4.6%, 18.6%), 7.8% (95% CI: 2.3%, 13.7%) and 18.1% (95% CI: 5.5%, 32.2%), respectively. Increasing levels of air pollutants were also associated with increased odds ratios of sore throat, cough, sputum, wheeze and dyspnea.

Conclusions

FeH2S may serve as a novel biomarker to detect adverse respiratory effects of air pollution. Our results provide potential important public health implications that ambient air pollution may pose risk to respiratory health in the context of high pollution levels in densely-populated cities in the developing world.

Introduction

Chronic obstructive pulmonary disease (COPD), characterized by persistent progressive airway obstruction and chronic inflammation (Chung and Adcock, 2008), has high prevalence worldwide and in China (Buist et al., 2007, Zhong et al., 2007) and will become the third leading cause of death worldwide by 2020 (Vestbo et al., 2013). Ambient air pollution is among the leading risk factors of COPD morbidity and mortality (Bentayeb et al., 2012, Viegi et al., 2006). A number of studies have used respiratory symptoms as the indicators to examine the respiratory effects of ambient air pollution in COPD (Viegi et al., 2006, Ko and Hui, 2012). However, most of these studies have been conducted in developed countries where air pollution levels are relatively low (Peacock et al., 2011).

Exhaled nitric oxide (FeNO) is a noninvasive measurement of airway inflammation that reflects eosinophilic airway inflammation among COPD patients (Barnes et al., 2010, Dweik et al., 2011). FeNO has been frequently used to assess the adverse respiratory effects associated with air pollution exposure (Scarpa et al., 2014), but only a few studies have used this marker to investigate air pollution effects in COPD patients (Adamkiewicz et al., 2004, Jansen et al., 2005, Chen et al., 2015). Along with FeNO, exhaled hydrogen sulfide (FeH2S) is another noninvasive biomarker that is involved in the pathogenesis of airway obstruction and may be used to estimate the neutrophilic airway inflammation in COPD (Wang, 2002, Chen et al., 2005, Calvert et al., 2010, Saito et al., 2014, Zhang et al., 2015). Specifically, a recent study found that COPD patients without eosinophilia had significantly higher levels of FeH2S than those with eosinophilia, suggesting that increased levels of FeH2S predicted a non-eosinophilic phenotype of COPD in the study population (Zhang et al., 2015). However, no study has ever used FeH2S as a surrogate to investigate the airway inflammation associated with air pollution exposure in COPD patients.

Ambient air pollution levels are high in Asian countries, especially in some Chinese megacities (Chan, 2008). For example, the annual average PM2.5 and PM10 concentrations in Beijing, China were 85.9 μg/m3 and 115.8 μg/m3 in 2014, respectively (Bureau, 2014). These levels are > 5 to 8 folds higher than the annual guidelines (10 μg/m3 for PM2.5 and 20 μg/m3 for PM10) recommended by World Health Organization. However, to our knowledge, no study has ever investigated the short-term effects of ambient air pollution on the airway inflammation and respiratory symptoms simultaneously in COPD patients in China or other Asian countries.

In the present study, we conducted a panel study to examine the associations between short-term exposure to high ambient air pollution and airway inflammation measured by FeNO and FeH2S and occurrence of respiratory symptoms in COPD patients during two study periods in Beijing, China.

Section snippets

Study participants and design

We used a panel study design to investigate the potential effects of short-term ambient air pollution exposures on the airway inflammation and respiratory symptoms in a group of COPD patients in the context of high pollution levels in Beijing, China. A total of 25 physician-diagnosed stable COPD patients were recruited from Peking University Third Hospital in Beijing during September to December 2013. Details on inclusion and exclusion criteria and data collection on demographics could be found

Descriptive statistics of exposure and health measurements

Baseline characteristics, results of FeNO and FeH2S measurements, and frequencies of respiratory symptoms of the study participants by period are shown in Table 1. Totally, they provided 215 measurements on FeNO and FeH2S and 794 person-day diaries over the entire study. The medians (IQR) of FeNO and FeH2S were 37.0 (12.3) ppb and 19.0 (15.9) ppb in Period 1 and 35.9 (7.0) ppb and 17.7 (4.7) ppb in Period 2, respectively. The occurrence rates of the respiratory symptoms sore throat, cough,

Discussion

The present study provides evidence for the short-term effects of exposure to several major air pollutants on airway inflammation and occurrence of respiratory symptoms simultaneously in COPD patients in the context of high pollution levels in China. We found that increasing levels of major air pollutants, including PM2.5, PM10 and SO2, were associated with increased airway inflammation measured by FeNO and FeH2S. Increasing levels of air pollutants were also significantly associated with

Conflict of interest statements

The authors declare on competing interests related to this project.

Acknowledgements

This project was supported by grants from the National Natural Science Foundation of China [Nos. 91543112, 81072267] and the special grant for Excellent Doctoral Dissertation from the Beijing Municipal Commission of Education [No. 20131000109].

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    These authors contributed equally to this work.

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