We read the article by Surendran et al., which studied the risk factors associated with COPD in an urban area of Trivandrum, Kerala, using spatial analysis, with great interest. Their study showed a significant association between proximity to main roads and prevalence of COPD, suggesting that proximity to road traffic may be a risk factor for developing COPD. Similar observations have been reported in the past from France, Japan, China, and Germany. Several studies have shown that, residing close (<100 m) to a major road has a detrimental effect on lung function and can increase the risk of allergic diseases and asthma.
We conducted a COPD prevalence study in 22 villages near Pune city among 3500 randomly selected male and female subjects above 30 years of age. All study participants were administered the BOLD (Burden of Lung Disease) questionnaire, and both pre and post bronchodilator spirometry was performed. The prevalence of COPD in our study was 5.1%, amongst which 85% were never smokers.
Two national highways pass through the 22 villages and using geospatial mapping analysis which is a technique used to process and map spatial data using GPS mapping, we found that the prevalence of COPD amongst people living closer to the highway was higher when compared to those who lived further away [Figures 1 and 2]. The consistency of this observation of higher COPD prevalence among those who live closer to the main road or highways as reported by Surendran et al., us and several other countries argues for a causal relationship. High levels of motor vehicular exhaust particles and gases and road dust when inhaled over several years may provide a biological plausible mechanism for the link between residential proximity to main road and COPD.
India is a vast country spread over 3,287,469 square kilometers, with one of the longest highways spread over 136,440 square kilometers. These highways carry more than 40% of the road traffic. Increasing urbanization accompanied by increasing number of roadways, may predispose people living in close proximity to a greater risk of developing COPD. This new evidence suggesting a causal association between proximity to main roads and COPD needs more attention.
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2. Peng Q, Zhang N, Yu H, Shao Y, Ji Y, Jin Y, et al. Geographical variation of COPD mortality and related risk factors in Jiading district, Shanghai Front Public Health 2021 9 627312
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