“Nature’s condition, rightly interpreted, reveals a society’s culture and traditions as directly as does a novel or a newspaper or a code of laws.”
– Roderick F. Nash
Adverse effects of air pollution on human health have been known ever since the “Great London Smog” in 1952. Mankind is paying for rapid industrialization by adversely affecting the air that we breathe. The developed world has been able to improve the environmental standards by following stringent norms and practices regarding engines, fuels, and industrial safety. However, the same cannot be said about developing countries. Delhi, the capital of India, has seen high levels of air pollution for the last several decades.
The number of registered vehicles in Delhi has doubled over the last 10 years. This, along with rapidly increasing numbers of small scale industries and inconsistently regulated construction work, has led to ever-increasing levels of air pollution in Delhi. The city has witnessed smog for the last few years.
Dr. G.C. Khilnani
Smog causing disruption of daily life and health hazards has been reported from Los Angeles, Beijing, and many other major cities around the world. The London Smog of 1952 caused approximately 4,000 deaths within 4 days (Davis D, et al. Environ Health Perspectives. 2002;110[12]:A734) and caused another 8,000 deaths over next few weeks to months (Bell ML, et al. Environ Health Perspectives. 2004;112[1]:6).
Dr. Pawan Tiwari
Common sources and pollutants with reference to Delhi
As in most cities around the world, rapid industrialization and increases in vehicles using fossil fuels are important contributors to ambient air pollution in Delhi. Additional sources of air pollution unique to Delhi include dust generation during building construction, ash generation from thermal power plants, crop residue burning in neighboring states, and burning of fossil fuels for domestic, as well as small scale, industrial use. Major pollutants include particulate matter (both PM2.5 and PM10), nitrogen oxides (NOx), carbon monoxide (CO), sulfur dioxide (SO2), and ozone (O3).
Delhi is distinct in its geographic location adjoining the Great Indian Desert (Thar) in the west and cool hilly regions in the north and east. This accounts for great seasonal variations in temperature, humidity, and wind speed. Also, being a landlocked territory, there are no moderating effects of sea breeze available to other metropolitan cities (like Mumbai and Chennai).
Dust storms during the summer from the neighboring state of Rajasthan cause an increase in suspended particulate matter (SPM). All these contribute to seasonal and climatic variations in air quality. In addition, the use of fire crackers during the festival of Diwali leads to dangerous levels of air pollution also.
Adverse health effects as witnessed in clinics and community
Many adults, without any prior history of respiratory illness, attended our outpatient department (OPD) with breathlessness, chest congestion, and wheezing requiring inhaled bronchodilators. A significant proportion of patients with previously diagnosed respiratory diseases (including COPD, bronchial asthma, or interstitial lung disease) reported to OPDs or emergency services with worsening cough, wheezing, and breathlessness. A few patients coming from outside Delhi for routine follow-up had exacerbation of COPD after coming to Delhi (personal observations).
We have previously reported increases in asthma, COPD, and acute coronary events (by 21.30%, 24.90%, and 24.30%, respectively) due to higher than acceptable levels of air pollutants in Delhi (Pande JN, et al. Indian J Chest Dis Allied Sci. 2002;44[1]:13). Another concerning development has been the increase in the number of persons being diagnosed with bronchial asthma in middle age, probably related to worsening air quality. Persons at extremes of age (young children and elderly) are particularly affected.
Studies in Delhi assessing ambient air pollution–related morbidity and mortality
Studies have used risk of mortality/morbidity due to air pollution model (Ri–MAP) to assess health impact of various air pollutants in Delhi. According to their estimates, there were 18,229 excess deaths in Delhi in the year 2010, more than 50% of which were due to cardiovascular or respiratory causes. Also, 26,525 excess hospital admissions due to COPD exacerbation could be attributed to ambient air pollution (Nagpure A, et al. Atmospheric Pollution Res. 2014;5[3]:1309).
Interventions: Work in progress
The Central Pollution Control Board convened an Expert Committee (Dr. Khilnani as a member) for formulation and implementation of Air Quality Index (AQI) in major Indian cities (http://cpcb.nic.in/FINAL-REPORT_AQI_.pdf).
Currently reported AQI is calculated by using the following parameters: sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter (PM10,PM2.5) averaged over 24 hours, along with ozone (O3) and carbon monoxide (CO), averaged over 1-8 hours. AQI is classified as good (0-50), satisfactory (51-100), moderate (101-200), poor (201-300), very poor (301-400), and severe (greater than 401).
AQI is reported daily in leading newspapers along with public and private news channels. Thanks to the mainstream and social media, smog has become a commonly understood word. Air pollution is a hot topic of discussion among people of all socioeconomic and demographic strata.
Children of almost all schools in Delhi pledged not to use firecrackers this Diwali. People are increasingly sharing taxis or carpooling. Utilization of public transport is gradually increasing.
The Delhi government ordered temporarily shutting off the only working thermal power plant in the megacity (source of 10%-15% of ambient air pollution). The government is also working on an action plan based on air quality, which includes both preventive and prohibitive measures.
Delhi Transport Corporation operates one of the world’s largest fleets of compressed natural gas–operated buses. Delhi Metro Corporation has been lauded by the United Nations for its efforts in reducing the carbon footprint and air pollution.
Yet, a lot needs to be done to improve the air quality in Delhi. Last mile connectivity remains a big hurdle; improving this will go a long way in promoting use of public transport. Implementation of methods to reduce particulate matter generation at construction sites, promoting use of vehicles using electricity or compressed natural gas, increasing parking charges for vehicles, banning the use of diesel-driven heavy vehicles in the city, road cleaning with vacuum cleaners to reduce PM 10 generation, increasing green areas, and promoting carpooling or taxi sharing are some other initiatives that need to be implemented on priority. Delhi and surrounding states need to strengthen awareness drives and norms to discourage crop residue burning on a priority basis.
Conclusion
Delhi’s poor air quality during this winter has indeed affected the respiratory health of the population. Healthy people, as well as those with preexisting respiratory diseases, are adversely affected. A series of actions at the personal and institutional level is required to control this menace.
Dr. Khilnani is Professor, and Dr. Tiwari is Research Officer, Department of Pulmonary Medicine & Sleep Disorders, All India Institute of Medical Sciences, New Delhi, India.