The various reports published on Air Pollution makes the threats so caused by the same crystal clear- be it the deaths of millions of people every year or the loss in GDP or countless other effects suffered by humans, animals and nature itself cannot be overlooked. The data so gathered by the World Health Organisation (WHO) shows the air quality nowhere close to the National Ambient Air Quality (NAAQ) standards thereby bringing in the public health crisis at a global level and the reasons behind the same being Air Pollutants are categorized and listed below:

  • Criteria Pollutants
  • Air Toxics
  • Biological Pollutants

                                                 CRITERIA POLLUTANTS

  • Carbon Monoxide: A colorless and odorless gas mainly formed by the incomplete combustion of fossil fuels, tends to reduce the level of oxygen in the blood carried by hemoglobin and has adverse health effects including severe headaches, chest pain, etc. The emissions from vehicles act as a major contributor to carbon monoxide formation leading to degradation of the environment.

( Graph showing the weight loss of rabbits exposed to carbon monoxide emission from exhaust system that used a catalytic converter)

  • Lead: Ore and metal processing are the core contributors of lead production which once consumed in by the human body gets deposited in the bones and has adverse health impacts including poor nervous system, malfunctioning of the kidney, low immunity, issues in reproductive and developmental systems, etc.
  • Nitrogen Dioxide: One of a group of highly reactive gases, nitrogen dioxide causes breathing disorders, irritate airways in the human respiratory system leading to coughing, sneezing, asthma, or difficult breathing. It also interacts with the oxygen in the air bringing in acid rain which further harms the ecosystem.
  • Ozone: Composed of three atoms of oxygen, Ozone can be classified as good and bad depending on where it originates and is further found. Where on one hand, good ozone protects us from the harmful rays of the sun, on the other, bad ozone tends to act as the main ingredient in the formation of smog.
  • Particles: Also known as atmospheric particulate matter, particulate matter (PM), particulates or suspended particulate matter (SPM), particles originate either naturally or by human activities including burning of fossil fuels, industrial processes, etc and tends to impact human health by causing nonfatal heart attacks, irregular heartbeat, aggravated asthma, decreased lung function, etc.
  • Sulfur Dioxide: EPA’s air quality standards have been developed to protect against the entire group of sulphur oxides whose largest sources are the burning of fossil fuels and various industrial activities which further harm the human’s respiratory system and causes difficulties in breathing as well.


Some major air toxics namely, formaldehyde, toluene, xylene, and polycyclic aromatic hydrocarbons (PAHs) are responsible for major health deterioration among human beings like birth defects, cancer, central nervous system defects, genetic damage, immunodeficiency, and disorders of the respiratory and nervous systems. All of the above-listed risks on human health are well known and considerable steps are being taken to minimize the same.


Some of the common biological pollutants often scattered indoors include animal dander, dust mite, cockroach parts, cat saliva, house dust, bacteria, and viruses, etc. All such pollutants tend to grow drastically under humid conditions, therefore it is highly recommended to maintain the normal humidity levels in our homes and immediate and continuous removal of any standing water near our places.


Air quality in India, measured by a tool named Air Quality Index can be defined as a number used by the government so as to make the public aware of the current state and the future forecast of air pollution. As the number increases it tends to denote the highly increased risk of the polluted air on people’s health, animals, and environment at large. Several countries in the world have got their own Air Quality Indices and their own quality standards.


With this, we may clearly conclude the various categories of air pollutants present in the contemporary era majorly impacting the quality of air, measured by the air quality index and the need to look out for effective solutions so as to improve the quality of air to be passed on to future generations.


  • Abbey, D. , Nishino, N. , McDonnell, W. , 1999, American Journal
  • Wark, K. , Warner, C. ,1981,