Air is a core element for the sustenance of life. The cleaner the air, the better your health and well-being. However, various sources, especially anthropogenic, are posing a significant threat to air quality.
Environmental pollution is the contamination in the environment that cause harm or discomfort to life or that damage the environment which can come in the form of chemical substances or energy such as noise, heat, or light. Pollutants can be generated by nature or man made but they are considered contaminants when in excess of natural level. Environmental pollution is not only problem of developing countries but spread in all over the world. Pollution reaches its most serious proportions in the densely settled urban-industrial centres of the more developed countries (kromm, 1973).
The enhancement in developmental activities and rapid urbanisation and industrialisation have resulted massive stress on natural resources’ and quality of life and the trend of increasing pollution in environment through deteriorating air, water and soil quality, higher level of noise, increasing vehicular emissions.
The industrialisation of the developing world is creating unsustainable pollution levels and rising pollution is ranked as the sixth most significant global trend. Developing countries will suffer the most from the weather – related disasters and increase waster stress caused (world economic forum report 2013).
The solution requires a technological and intellectual revolution; an alternative route to economic prosperity that preserves resources and limits pollution to be developed before it is too late. India has experienced rapid growth since 1991. In 2007 India was reflecting a 42.67% growth during in this 20 year (Economic survey of India, 2010-11, Ministry of Finance). In 2005 India became fifth largest polluter and remains in this position (world resources institute, World Economic forum).
The impact of rising toxins in the air is clearly visible as according to Lancet study in 2012, air pollution was found to be the sixth biggest killer with an annual estimated toll of 66million.
It is shocking to know that out of the top twenty most polluted cities in the world, thirteen are in India- Allahabad, Agra, Lucknow, Kanpur, Amritsar etc. are among the list of top 20 most polluted cities in the .Other major cities of neighbouring countries of India i.e., Karachi, Rawalpindi and Peshawar in Pakistan, Beijing in China are also in the list Pollution is a real threat to health and well-being of mankind. Studies by WHO reveal that globally seven million people died because of exposure of air pollution. Those include death due to exposure to toxic pollutants both inside house and in the environment.
AIR POLLUTION and AIR POLLUTANATS
The atmosphere is an insulating blanket around the earth. This evolving mixture of gases contains huge numbers of solid and liquid particles (D.S. Lal, Climatology). It is the source of the essential gases, temperature, rain, air and protect from UV rays and meteors (Ecology and Environment, P.D. Sharma). Growth in population, rapid growth in urbanisation and industrialisation, rising demands for energy and motor vehicles are worsening air pollution level (Mishra, 2003). He also added that some other factors play vital role in air pollution such as poor environmental regulation, less efficient technology of production, congested roads, and poor maintenance of vehicle. Polluted air contents one, or more, hazardous substance, pollutants or contaminant that creates a hazard to general health (health and energy, 2007). The main pollutants found in the air include, particulate matter, PAHs, lead, ground level ozone, heavy metals, SO2, CO, NO2, and benzene (European Public Health Alliance, 2005).
AIR POLLUTION TREND IN INDIA
More than half of the world’s population lives in urban areas. It is estimated that by 2030 there will be 41 megacities and most of them will be located in developing countries. The megacities in India (Delhi, Mumbai, and Kolkata) collectively have >46 million inhabitants.
Increasing population and prosperity results in rapid growth of the already large consumption of energy and other resources, which contributes to air pollution, among other problems. Megacity pollution outflow plumes contain high levels of criteria pollutants (e.g. Particulate matter, SO2, NOx), greenhouse gases, ozone precursors and aerosols; which can affect the atmosphere not only on a local scale but also on regional and global scales. In the current study, emissions and concentration trends of criteria and other air pollutants (polycyclic aromatic hydrocarbons, carbon monoxide and greenhouse gases) were examined in the three Indian megacities. Further, various policies and control strategies adopted by Indian Government are also discussed to improve air quality.
Decreasing trends of SO2 was observed in all three megacities due to decrease in the sulphur content in coal and diesel. However, increasing trend for NOx was found in these megacities due to increase in number of vehicles registered and high flash point of CNG engines, which leads to higher NOx emission. In terms of SPM and PM10, highest emissions have been found at Kolkata, whereas highest ambient concentrations were recorded in Delhi.
For Mumbai and Kolkata fluctuating trends of SPM concentrations were observed between 1991 and 1998 and stable afterwards till 2005; whereas for Delhi, fluctuating trend was observed for the entire study period.
However, several steps have been taken to control air pollution in India but there is a need to focus on control of non-exhaust emissions including municipal solid waste and biomass burning in the megacities and surrounding areas.
Taking the WHO air quality guidelines into consideration, such elevated values of PM2.5 can increase long-term mortality risk by 15%.
For the past few decades, the world has been bustling with various human activities that tremendously contributed to air pollution. But 2020 brought everything to a halt. The coronavirus pandemic started spreading like wildfire and many countries resorted to lockdown.
A boon of the coronavirus situation, if any, is the positive impact it had on the environment because of the lockdown imposed to prevent the spread of the disease. On March 25, 2020, the Government of India placed its population of more than 1.3 billion citizens under lockdown in an effort to curb the spread of the COVID-19.
To explore whether the lockdown alleviated the pollution, we have compared the AQI data of March-April of the year 2019 and 2020. The daily average AQI value for March- April 2019 is 656 and this value drastically reduced to more than half to 306 in March-April 2020.
The figure below on the right shows the tropospheric NO2 concentration over India, while the left figure shows the concentration on the same day of the previous year.
Every year, In the month of April, the NO2 concentration is typically on the higher side for states such as Delhi-NCR, some regions of Jharkhand, Chhattisgarh, Odisha, Ahmedabad, and Goa.
However, in 2020, we can see that there is a significant decrease in the emitted NO2 over the Northern and western regions as well as in Delhi and Ahmedabad.