1: Urban Air Quality
Rapid urbanization and growing population can give rise to more and more air pollution. Its sources are majorly from urban areas. Let's see where does the pollution originate from.
Places across the world are often categorised as urban or rural. The Census of India[1] defines urban area as an area with-
- Minimum population of 5,000 persons
- At least 75% of the male main working population is engaged in the non- agricultural pursuits.
- Population density of at least 400 people per Km2.
The quality of air in these urban areas is termed as ‘urban air quality’. Urban air quality indicates how “clean” the air is inside the cities, in a densely populated locality/area where the level of activity is recognized as “urban”.
It is a well known fact that humans and other living beings need clean air to survive. But as the population density increases, the air quality may deteriorate. The urban air quality also varies from its proximity to the industrial zones and non-industrial zones.
The quality of air can affect human health as well as the climate of the area. The incidences of the Great Smog in London and Bhopal Gas Tragedy made us realise the importance of clean air. The event spurred some of the first governmental actions to reduce emissions from fuel combustion, industrial operations, and other manmade sources.
Did you know?
According to the World Health Organization (WHO) 4.2 million deaths every year occur as a result of exposure to ambient (outdoor) air pollution. This is more prominent in Urban areas.[2]
Rural India is being sidelined: Out of the 600 plus air quality monitoring stations, the Central Pollution Control Board (CPCB) set up across the country, there are none in rural areas. The lack of adequate monitoring and measurement systems leaves the air quality challenges in rural India uncovered.
Air pollution is defined as contamination of indoor and outdoor by any chemical, physical and biological elements that alters the natural atmospheric conditions. The physical, chemical or biological elements in solid, liquid or gaseous state present in the atmosphere in concentrations that can cause damage to all living beings, property and the environment are called ‘air pollutants’. The sources of pollutants are more in urban areas compared to rural areas. Also, the ability for the pollutants in the air to be dispersed are limited by physical constraints of the urban environment.
The sources of urban air Pollution are broadly categorised into two types-
1. Natural sources:
As the name suggests, the pollutants entering the air due to nature and natural occurrences. The sources include volcanic eruptions, thunder, dust from the earth’s surface and naturally occurring particulate matter.
2. Anthropogenic sources:
In this case, the pollutants arise due to human activities. The anthropogenic sources are further categorised into the following-
a. Transportation: Vehicular emission continues to be one of the major causes of air pollution in urban areas. This includes:
- Use of Private vehicles over public transport
- Use of worn out or old vehicles
- Vehicles operating on non- environmental friendly fuel
- Damaged roads increasing the particulate matter in the air
FACT: According to studies, vehicles annually contribute about 290 gigagrams (Gg) of PM2.5. At the same time, around eight per cent of total greenhouse gas (GHG) emissions in India are from the transport sector, and in Delhi, it exceeds 30 per cent[3]
b. Domestic Use: Though the world has technologically advanced, many parts of the world are dependent on fossil fuels or biomass like wood, charcoal and coal, which are burnt and being used for cooking and heating.
- Firewood used for cooking purposes releases harmful particulate matter and climate - warming pollutants into the atmosphere.
- Inefficient stoves fueled by kerosene, biomass (wood, animal dung, crop waste) and Kerosene based lamps used at households affect indoor air quality.
FACT: Household air pollution was responsible for an estimated 3.2 million deaths per year in 2020, including over 237000 deaths of children under the age of 5. [4]
c. Industrialization: The development is often linked to industrialization but with great advancement , comes set-backs. The industries release various gases due to burning of fossil fuels and chemical usage. These gases can either react with each other or other atmospheric constituents , resulting in the degradation of the air quality. It is estimated that around 80 different toxins can be found in the air emitted by factories. The list includes pollutants like asbestos, dioxins, lead and chromium.
d. Agricultural Burning: Agriculture has been a part of our civilization for a long time. Agricultural practices like Jhum cultivation and the traditional practices of agriculture include burning of vegetation for clearing land. The combustion of plants and agricultural residue releases CO2 , NO2, CH4(Methane) and other toxic gases into the atmosphere impacting the urban air quality.
Did You Know?
Beauty Products also cause air pollution![5] A recent study suggests that the use of beauty products also contributes to urban air pollution. Most of the cosmetics and perfumes contain VOCs, which are released during their use and contribute to urban air pollution. With more population, the use of these beauty products is increasing and so is the pollution.