Ambient Carbon Monoxide Associated with Reduced Risk of COPD Hospitalizations

The authors declare we have no actual or potential competing financial interests. Abbreviations: Author's contributions to the study: LWT, KFH and ITY defined the research theme. LWT, KFH, WT, HQ and VCP analyzed the data, interpreted the results and wrote the paper. JCC and PKL co-worked on associated data collection and their interpretation. Abstract Recent experimental and clinical studies suggested that inhaled carbon monoxide at lower concentrations may have beneficial anti-inflammatory effects. Inhaled carbon monoxide has the potential to be as a therapeutic agent for chronic obstructive pulmonary diseases (COPD). Population-based epidemiological studies of environmentally relevant carbon monoxide exposure, however, generated mixed findings. We conducted a time series study in Hong Kong to estimate the short-term association of ambient carbon monoxide with emergency hospitalizations for COPD. We collected daily emergency hospital admission data and air pollution data from January 2001 to December 2007. We used log-linear Poisson models to estimate the associations between daily hospital admissions for COPD and daily average concentrations of carbon monoxide, controlling for other traffic related co-pollutants: nitrogen dioxide and PM2.5. Results showed that ambient carbon monoxide was negatively associated with the risk of COPD hospitalizations. After adjustment for nitrogen dioxide or PM2.5, the negative associations of carbon monoxide with COPD became stronger. Therisk estimates were similar between females and males. In conclusion, short-term exposure to ambient carbon monoxide was associated with decreased risk of hospitalizations for COPD, suggesting some acute protection of carbon monoxide exposure against COPD exacerbations.