Impact of Air Pollution on Human Health

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June 28, 2024

Why in news?

Recently, the State of Global Air (SoGA) 2024 was released which offers a stark reminder of the significant impacts air pollution has on human health.

What is air pollution?

  • Air pollution – It is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere.
  • Common sources – Household combustion devices, motor vehicles, industrial facilities and forest fires are common sources of air pollution.
  • The major outdoor pollution sources include residential energy for cooking and heating, vehicles, power generation, agriculture/waste incineration, and industry.
  • Pollutants - Pollutants of major public health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide.
  • Impact on climate – Many of the drivers of air pollution (i.e. combustion of fossil fuels) are also sources of greenhouse gas emissions.
  • Impact on human health - Outdoor and indoor air pollution cause respiratory and other diseases and are important sources of morbidity and mortality.
  • Polluted air is a big trigger for pneumonia and other respiratory infections and allergic diseases in children.
  • There is a strong connection between long-term exposure to traffic-related air pollution and early death due to cardiovascular diseases and lung cancer, asthma onset in children and adults, and acute lower-respiratory-tract infections in children.

WHO data show that almost all of the global population (99%) breathe air that exceeds WHO guideline limits and contains high levels of pollutants, with low- and middle-income countries suffering from the highest exposures.

State of Global Air (SoGA) 2024

  • It is an annual tracker of health impact of air pollution.
  • Prepared by – It is a collaborative assessment by the
    • US-based Health Effects Institute (HEI)
    • Institute for Health Metrics and Evaluation’s Global Burden of Disease (GBD) project.
  • This has been produced for the first time in partnership with UNICEF.
  • Data source – These results are linked to the Global Burden of Disease (GBD) 2021 report which estimated about 200 countries.
  • Assessment – It usually assess the impact of Particulate Matter (PM2.5) and Ozone on human health.
  • This 2024 report also covers the impact of nitrogen oxides (NO2).


What are the key findings of the report?


  • During the pre-pandemic phase (1990 to 2019) – The order of the leading global causes of death were ischemic heart disease, stroke, chronic obstructive pulmonary disorder (COPD), and lower respiratory disease. 
  • Post pandemic in 2021 – Covid-19 changed the order with age-standardised mortality from COVID ranking second after ischemic heart disease, and stroke and COPD dropping to third and fourth place, respectively. 
  • Impacts of air pollution on human – It become the second largest killer globally after blood pressure, recording a dubious tally of 8.1 million deaths in 2021.


  • Impact on children under five years - With more than 700,000 deaths, air pollution become the second leading risk factor after malnutrition globally.
  • As many as 500,000 of these child deaths are linked to household air pollution from cooking indoors using dirty fuels in Africa and Asia.
  • Polluted air is a big trigger for pneumonia and other respiratory infections and allergic diseases in children.


  • Impact of Climate Change – It can exacerbate the health burden of non-communicable diseases, including heart and lung diseases, during heatwaves.

What is the status of pollutants causing air pollution?

  • Even though PM2.5 (both ambient and household together) account for more than 90% of the total air pollution disease burden, NO2 and ozone are the growing risk factors globally.

Status of NO2 in Air pollution

  • Higher exposure to NO2 shows the growing risk from traffic exhaust in densely populated urban areas.
  • Seven of the 10 countries with the highest NO2 exposures are in the high income countries in West Asia.
  • The highest exposures to NO2 have been noted in countries with high socio-development index, including Singapore, Japan and Canada.
  • Impact on children – NO2 is a leading risk factor for the development of childhood asthma.
  • About 55% of 194 countries studied do not yet meet the annual WHO Air Quality Guidelines of 10 µg/m3, resulting in 42% of the world’s population being exposed to unacceptable levels.
  • Impact of climate – It is a catalyst for formation of ozone, yet another very harmful gas.
  • NO2 reacts with other chemicals in the atmosphere to produce both particulate matter and ozone.

Status of Ozone in Air pollution

  • Ozone levels have also increased in South Asia.
  • Impact of Climate change – The chemical reactions that form ozone increase when the air is warmer, especially during heatwaves.
  • Evidence shows that ozone spikes during heatwaves in China and Europe.
  • Exposure – The proportion of population experiencing high ozone exposures is also increasing in India, Nigeria, Pakistan, and Brazil.
  • Impact on vegetation – It can reduce crop yields, damage biodiversity, and undermine food security and nutrition.
  • Impact on humans – In 2021, ozone was responsible for 56% of all global ozone deaths reported in South Asia.
  • Exposure to ozone is associated with an increased risk of both acute and chronic respiratory illnesses.
  • India – It has recorded about 237,000 ozone related deaths.
  • In 2021, nearly 50% of all ozone-related COPD deaths were in India, followed by China and Bangladesh.

Status of PM 2.5 in Air pollution

  • Evidently, nearly 20% of the global ambient PM2.5 is attributed to household air pollution.
  • Impact on humans – India and China have recorded 2.1 million and 2.3 million deaths respectively and together account for nearly 55% the total global disease burden from particulate matter.

What lies ahead?

  • Emulate the successful policy decisions – There has been a 61% reduction in the age-standardised death rate from household air pollution.
  • This improvement has been possible due to growing access to clean energy for cooking, grid electricity, cleaner-burning cookstoves, and cleaner fuels.
  • Tackle air pollution – It can be done by reducing toxic emissions and greenhouse gases, which will improve public health and combat climate change. 


  1. Down To Earth| Air Pollution is 2nd Leading Risk Factor for Children
  2. WHO| Air Pollution
  3. State of Global Air| State of Global Air 2024 Report


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