What is air pollution? It is simply the contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere. There are many sources of air pollution and household combustion devices, motor vehicles, industrial facilities and forest fires are some of the common sources. Polluted air brings adverse health impacts to humans as well as to the environment. Pollutants of major public health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide. Considering individuals, air pollution can affect lung development and is implicated in the development of emphysema, asthma, and other respiratory diseases, such as chronic obstructive pulmonary disease (COPD). Several million are known to have died due to the direct or indirect effects of Air pollution. According to World Health Organization (WHO), almost all of the global population (99%) breathe air that exceeds WHO guideline limits and and contains high levels of pollutants. Interestingly, low- and middle-income countries suffering from the highest exposures of air pollution. The WHO estimates that: 4.2 million die prematurely every year from outdoor (ambient) air pollution. 3.8 million die from indoor air pollution. The figure 1 shows the death from all sources of air pollution in the world.


Figure 1. Death from air pollution in the world.
Does air pollution affect cities?
A study of air pollution and crime in 9,360 US cities shows that air pollution increases crime rate. The study reveals that polluted air increases anxiety, which can in turn lead to a rise in criminal or unethical behavior. We can find 25 most polluted cities in the world. We see most of them are in the developing countries. Of them 9 were in India, 5 in China, and 2 in Pakistan. The most polluted city in the world remained in Pakistan, with Lahore averaging 108 micrograms of PM2.5. According to WHO, the city of Bhiwadi in northern India had the most polluted air in the world in 2021, with an average PM2. 5 concentrations of 106.2 micrograms per cubic meter of air (μg/m³). While some countries work to mitigate air pollution following WHO guidelines, we can see China’s number increased. Some countries like Kuwait, Afghanistan, and Mali which were in the last 2021 list were fell off from 2022 list of polluted countries, due to their work of mitigating air pollution. Some new countries were featured on the list in this 2022 update include Nepal, Saudi Arabia, Bahrain, Iraq, Tajikistan, Bangladesh, Mexico, Mongolia, and Uganda. All the ranked polluted cities had average air quality many times above the WHO recommended healthy limit. Many of the cities with the worst air quality are in similar geographical areas on the globe.
Air Quality Index (AQI)
The Air Quality Index (AQI) is used for reporting daily air quality. It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. The AQI focuses on health affects you may experience within a few hours or days after breathing polluted air. It is an index for reporting air quality on a daily basis. It is a measure of how air pollution affects one’s health within a short time period. The main purpose of the AQI is to help people know how the local air quality impacts their health. The Environmental Protection Agency (EPA) calculates the AQI for five major air pollutants. They are the Ground-level ozone; Particle pollution/particulate matter (PM2.5/pm 10; Carbon Monoxide; Sulfur dioxide and Nitrogen dioxide. EPA follows these calculations to develop AQI to show the national air quality standards, to safeguard public health (figure 2).


Figure 2: AQI and air pollution level.
Air pollution and economic impacts.
Air pollution takes its toll on the economy in several ways: it costs human lives, it reduces people’s ability to work, it affects vital products like food, it damages cultural and historical monuments as well as reduces the ability of ecosystems functions. There are many estimations show the economic impacts of air pollution in different countries of the world. In 2015, WHO and OECD estimated that the economic cost of premature death and disability from air pollution in Europe is close to USD 1.6 trillion. In China, this is estimated at $900 billion a year when it is $600 billion for USA. According to Greenpeace report relates to the costs of air pollution from fossil fuels, both human and economic, burning gas, coal and oil results in three times as many deaths as road traffic accidents worldwide and it is estimated that air pollution has a $2.9 trillion economic cost, equating to 3.3 percent of the world’s GDP. In 2018, the report estimates that it was linked to 4.5 million deaths with PM2.5 pollution also responsible for 1.8 billion days of work absence, 4 million new cases of child asthma and 2 million preterm births. Figure 3 shows the economic burden of air pollution for some leading countries.


Figure 3. Economic burden of air pollution, 2018.
How can we reduce air pollution in the world.
There are new technologies that contribute to emissions’ reductions are constantly being developed. Setting emission limit values for air pollutants, as done under the different Protocols of the Convention, have proven to be an effective tool in mitigating air pollution. In the long run, it is important to work on the environmental policies that leads to clean energy productions and technologies. A larger market for clean technologies will reduce the economic cost of air pollution, contributes to several development goals and ultimately will yield substantial benefits.
What can you do to reduce air pollution?
As a responsible global citizen, you can make a significant contribution to reducing global air pollution by doing your daily activities more carefully Some of these are the following and can be performed easily. You may not be available for all, but you can definitely do some of them and help clean up the air for all.
- Use public transportation instead of private transportation that helps in less air pollution. It also saves fuel and gas for other uses. Also, it makes less traffic in roads.
- Turn off the light and minimize energy use. That helps in saving more energy as well as reducing pollution.
- Maximize your habit of recycling and reuse of resources. That leads reducing production and ultimately reduce emissions and save resources.
- Minimize the use of plastic bags that leads for higher pollution. It is better to switch to paper bags instead as they decompose easily and are recyclable.
- Reduce forest fires and smoking to minimize the air pollution. Colleting garbage and getting it fire can be stopped and think of a better way of using them. Eg. Compost.
- Minimize the use of air conditioners as much as possible and switch to fans. The AC’s takes a lot of energy and emits a lot of heat which is bad for the environment.
- Using filters for chimneys will reduce air pollution and reduce the effect of harmful gases absorbing in the air.
- Avoid using crackers especially in the festival times that brings lots of air pollution. It brings sound pollution as well.
- Minimize using of products with chemicals. These chemicals may pollute the air we breathe, the water we drink, and the food we eat. They may have entered into forests and lakes, destroying wildlife and changing the ecosystems as well.
- Carryout and encourage afforestation. Plant and grow trees as much as possible. The practice of planting trees provides a lot of benefits to the environment and helps with the release of oxygen.