Gasping for breath in urban jungles
Air pollution is associated with an increased risk of acute respiratory infections and decreased lung function
Dr Amit Kumar Mandal


Children exposed to passive smoking and traffic pollution are at an increased risk of asthma. Thinkstock

Indian cities are growing rapidly, owing to the expanding economic base. This has led to an increase in the ownership and use of motor vehicles with a subsequent rise in the levels of air pollution. Exposure to air pollutants is known to be harmful to health, in general, and to the lungs, in particular.

Harmful effects of air pollution on human health have been recognised for centuries. Globally 8,000 people die every day from diseases related to air pollution exposure. Each year 60,000 deaths in the USA and 500,000 deaths in China occur due to air pollution.

The London fog incident in 1952 conclusively established an association between air pollution and increased mortality. More than 100 published studies have assessed the relationship between exposure to PM levels (Particulate Matter) and excess mortality and morbidity in humans. Each 10µg/m3 increase in annual average PM2.5 level may lead to 4 per cent, 6 per cent and 8 per cent rise in the risk of all-cause, cardio-pulmonary, and lung cancer mortally, respectively.

Air pollution is associated with increased risk of acute respiratory infections, the principal cause of infant and child mortality in developing countries. Morbidity ranges from pulmonary function decrements to respiratory symptoms, and to hospital and emergency department admissions. Several epidemiological studies have described a close association between traffic flow and respiratory symptoms and decreased lung function.

Respiratory symptoms are of two types

Upper respiratory symptoms: Runny and stuffy nose, sinusitis, sore throat, wet cough, dry cough, cold head, fever, burning or red eyes.

Lower respiratory symptoms: Wheezing, phlegm, shortness of breath, chest discomfort or pain.

Most of the respiratory diseases underlying these symptoms are caused by bacterial, fungal or viral infections, or structural or functional damage to the respiratory system. Very often the symptoms of a multi-factor respiratory disease like asthma or chronic obstructive pulmonary disease (COPD) are aggravated following exposure to air pollutant. Cough is an important symptom frequently reported following exposures to air pollution. It is a reflex response to irritation from mucous or any foreign particle in the upper respiratory tract.

Various symptoms and impact on respiratory diseases are as follows:

  • Decline in lung functions in adult asthmatics was associated with increased concentration of transitional metal like iron. (Dusseldorp, 1995).

  • High prevalence of chronic cough, phlegm and sinusitis reported among garage workers and taxi drivers exposed to vehicular exhaust. (Bener, 1998, UAE).

  • Chest tightness and dyspnea with rhinitis and nose, throat irritation and lung function abnormality in shoe manufacturing plant workers where benzene level was higher than allowable limit. (Zuskin, 1997, Croatia).

  • Chronic respiratory symptoms excepting wheeze and reduced lung function were significantly more common in high pollution zones. (Chhabra, 2001, Delhi).

  • Study on early-life exposure to outdoor air pollution and respiratory health, ear infections, and eczema in infants: support the hypothesis that in utero orearly-life exposure to ambient air pollution may increase the risk of upper and lower respiratory tract infections in infants. (INMA Study 2013,Spain).

  • Parental smoking and children’s respiratory health suggested independent effects of pre- and post-natal tobacco smoke exposures. (Pattenden, 2006).

  • High prevalence of cough, sinusitis, bronchitis and asthma has been found in association with traffic-related air pollution. (Basu, 2001, Kolkata).

  • Strong association between severe asthma symptoms and breath concentration of benzene in children. (Delefino, 2002).

  • Increased asthma, cough and wheeze in children who were additionally exposed to environmental tobacco smoke along with high vehicle traffic. (Nicolai, 2003, Germany).

  • Decreased spirometric lung function in polluted commercial and residential areas while normal lung function was found in relatively clean area of IIT campus. The peak expiratory flow rate (PEFR) was also markedly reduced in urban subjects of this study. (Sharma, 2004, Kanpur).

  • Asthma and bronchoconstriction have been linked to cumulative exposures to exhaust from diesel-fuelled engines and occupational exposures to VOCs. (Riedl et al., 2005 and Cakmak, 2004).

  • SPM and RSPM levels of Delhi had significant positive correlation with COPD (rho=0.476 and 0.353 respectively) (Agarwal, 2006)

  • As much as 3.9 per cent of adult individuals of Delhi had COPD, compared with only 0.8 per cent of control subjects, indicating nearly 5-times more relative risk in the city. (Central Pollution Control Board, India, August 2008).

— The writer is Additional Director, Pulmonology, Sleep & Critical Care, Fortis Hospital, Mohali.





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