Association between Air Pollution, Body Mass Index, Respiratory Symptoms and Asthma Among Adolescent School Children Living in Delhi, India

Abstract

Background: Delhi is one of the most polluted cities in the world with annual average ambient PM10 and PM2.5 levels exceeding the WHO standards by over 15-fold. We aimed to study the prevalence of respiratory and allergic symptoms and asthma among adolescent children living in Delhi (D) and compare it with children living in lesser polluted cities of Kottayam (K) and Mysuru (M) located in southern India. Methods: 4361 boys and girls between the ages of 13-14 and 16-17 years from 12 randomly selected private schools from D, K and M were invited to participate. Modified and expanded ISAAC questionnaires (Q) were filled by the students who also performed spirometry using the ultrasonic flow-sensor based nDD Spirometer. Results: 3157 students (50.4% boys) completed the Q and performed good quality spirometry. The prevalence of asthma among children living in Delhi was 21.7% using the ISAAC Q and 29.4% on spirometry. This was accompanied by significantly higher rates of self-reported cough, shortness of breath, chest tightness, sneezing, itchy and watery eyes, itchy skin and eczema among Delhi children (vs K-M, all p values<0.05). Delhi children were more overweight and obese (39.8% vs 16.4%, p<0.0001) and this was the only risk factor that was strongly associated with asthma (OR: 1.79; CI: 1.49-2.14), with a more pronounced effect in Delhi children (p=0.04). FEV1 and FVC values were significantly higher in Delhi children (vs K-M p<0.0001). Preserved ratio impaired Spirometry (PRISm) was more common in K-M children (p<0.0001). Conclusion: Adolescent children living in the polluted city of Delhi had a high prevalence of asthma, respiratory symptoms, allergic rhinitis and eczema that was strongly associated with a high body mass index (BMI). Our study suggests an association between air pollution, high BMI and asthma/allergic diseases, which needs to be explored further. Funding Statement: Shakti Sustainable Energy Foundation, India Declaration of Interests: None of the authors have any conflicts of interest to declare for this study. Ethics Approval Statement: The study was approved by the Ethics Committee of Sir Gangaram Hospital, Delhi.