Full length articleShort-term exposure to high ambient air pollution increases airway inflammation and respiratory symptoms in chronic obstructive pulmonary disease patients in Beijing, China
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].
References (41)
- et al.
Exhaled nitric oxide in pulmonary diseases: a comprehensive review
Chest
(2010) - et al.
International variation in the prevalence of COPD (the BOLD Study): a population-based prevalence study
Lancet
(2007) Air pollution in mega cities in China
Atmos. Environ.
(2008)- et al.
Endogenous hydrogen sulfide in patients with COPD
Chest
(2005) - et al.
Effects of air pollution on exhaled nitric oxide in children: results from the GINIplus and LISAplus studies
Int. J. Hyg. Environ. Health
(2014) - et al.
Winter air pollution and disease parameters in advanced chronic obstructive pulmonary disease panels residing in Denver, Colorado
J. Allergy Clin. Immunol.
(2005) - et al.
Acute COPD exacerbations
Clin. Chest Med.
(2014) - et al.
Fine particulate matter, temperature, and lung function in healthy adults: findings from the HVNR study
Chemosphere
(2014) - et al.
Association between air pollution exposure and exhaled nitric oxide in an elderly population
Thorax
(2004) - et al.
ATS/ERS recommendations for standardized procedures for the online and offline measurement of exhaled lower respiratory nitric oxide and nasal nitric oxide, 2005
Am. J. Respir. Crit. Care Med.
(2005)
Adverse respiratory effects of outdoor air pollution in the elderly
Int. J. Tuber. Lung Dis.
BMEP. Beijing Environmental Statement 2013
Prior SO2 exposure promotes airway inflammation and subepithelial fibrosis following repeated ovalbumin challenge
Clin. Exp. Allergy
Novel insights into hydrogen sulfide–mediated cytoprotection
Antioxid. Redox Signal.
Fine particulate matter constituents, nitric oxide synthase DNA methylation and exhaled nitric oxide
Environ. Sci. Technol.
Multifaceted mechanisms in COPD: inflammation, immunity, and tissue repair and destruction
Eur. Respir. J.
Breastfeeding as a modifier of the respiratory effects of air pollution in children
Epidemiology
An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FENO) for clinical applications
Am. J. Respir. Crit. Care Med.
Respiratory effects of air pollution in chronic obstructive pulmonary disease: a three month prospective study
Thorax
Critical review of the human data on short-term nitrogen dioxide (NO2) exposures: evidence for NO2 no-effect levels
Crit. Rev. Toxicol.
Cited by (0)
- 1
These authors contributed equally to this work.