Over 9 Million Lives Could Be Saved Every Year if Countries Met WHO Air Quality Guidelines: A Wake-Up Call on the Global Air Pollution Crisis

Why in news?

A new study by researchers from the University of Cambridge has revealed that more than 9 million premature deaths could potentially be prevented or postponed every year in low- and middle-income countries if they met the World Health Organization's (WHO) recommended air quality guidelines.

Key Facts 

What did the researchers do?

• The researchers combined information from three major areas:
  • Air pollution data: Existing concentrations of PM2.5 and NO₂.
  • Population data: Population size and exposure to pollution.
  • Health data: Evidence linking air pollution with premature deaths and diseases.

What is Air Pollution?

• Air pollution refers to the presence of harmful substances in the atmosphere at concentrations that can negatively affect human health, other living organisms and the environment. These harmful substances are called air pollutants.
• They may include particulate matter, carbon monoxide, sulphur dioxide, nitrogen dioxide, ground-level ozone and volatile organic compounds.

Understanding PM2.5: The Most Dangerous Fine Particles

• PM2.5 stands for Particulate Matter 2.5.
• It refers to extremely small airborne particles with a diameter of 2.5 micrometres or less.
• To understand how small these particles are, consider this:
• A human hair is approximately 50–70 micrometres thick.
• PM2.5 particles are 2.5 micrometres or smaller.
• Therefore, many PM2.5 particles are far smaller than the width of a human hair.

Where does PM2.5 come from?

Why is PM2.5 particularly harmful?

• Enter deep into the respiratory system.
• Reach the alveoli, the tiny air sacs in the lungs.
• Cause inflammation and oxidative stress.
• Contribute to cardiovascular and respiratory diseases.
• Increase the risk of premature death after prolonged exposure.

What is Nitrogen Dioxide (NO₂)?

• Nitrogen dioxide is a reddish-brown, highly reactive gas belonging to the group of nitrogen oxides (NOx). It is mainly produced through high-temperature combustion of fossil fuels.
• Major sources of NO₂ are motor vehicle exhaust, particularly diesel vehicles, thermal power plants, industrial combustion, gas stoves and heaters and other fossil-fuel combustion activities.
• Exposure to nitrogen dioxide can irritate the respiratory tract, increase airway inflammation, worsen asthma, reduce lung function and increase susceptibility to respiratory infections.

What are WHO Air Quality Guidelines?

• The World Health Organization (WHO) released its updated Global Air Quality Guidelines in September 2021, replacing the earlier guidelines issued in 2005.
• These guidelines provide scientifically recommended limits for major air pollutants to protect human health.
• The 2021 revision was important because scientific evidence showed that air pollution can cause serious health damage even at lower concentrations than previously understood.

Major WHO Air Quality Guidelines (2021)

Why did WHO revise its guidelines?

• The 2021 revision was based on growing scientific evidence about the harmful effects of air pollution.
• For example:
  • The annual PM2.5 guideline was reduced from 10 to 5 µg/m³.
  • The annual PM10 guideline was reduced from 20 to 15 µg/m³.
  • The annual NO₂ guideline was reduced from 40 to 10 µg/m³.
  • This means WHO now recommends substantially cleaner air to protect public health.

How does Air Pollution affect Human Health?

What did the Cambridge study discover beyond saving lives?

• The study highlights that the benefits of cleaner air extend far beyond preventing premature deaths.
• If countries achieved the WHO's recommended PM2.5 guideline levels, researchers estimated that the following new disease cases could be avoided or postponed in a year:
• Estimated annual new cases potentially avoided or postponed by meeting the WHO PM2.5 guideline in the 136 countries studied.

Economic benefits of achieving WHO Air Quality Guidelines

• Air pollution is not only an environmental and health issue; it is also an economic problem.
• Pollution-related illnesses create financial pressure through increased medical expenditure, hospitalisation and long-term treatment, reduced workforce productivity, absenteeism from work and premature loss of working-age individuals.

Why are Low- and Middle-Income countries more vulnerable?

Major sources of air pollution in India

How serious is PM2.5 exposure in India?

• A study published in The Lancet Planetary Health in 2025, using data for 2009-2019, estimated that:
• The annual median population-weighted PM2.5 concentration in India was 38.9 µg/m³.
• The entire population lived in areas exceeding the WHO annual guideline of 5 µg/m³.
• Approximately 81.9% of the population lived in areas exceeding India's annual PM2.5 National Ambient Air Quality Standard of 40 µg/m³, according to the study's analysis.

Major government initiatives

International Efforts to Control Air Pollution

Significance of the Cambridge Study

• Public health: Cleaner air can prevent millions of premature deaths.
• Healthcare savings: Reduced illness can lower medical expenditure.
• Economic productivity: Healthier populations can participate more effectively in the workforce.
• Social equality: Vulnerable populations in low- and middle-income countries can benefit substantially from cleaner air.

Challenges in Achieving WHO Air Quality Guidelines

• Fossil-fuel dependence: Coal and petroleum remain major energy sources.
• Rapid urbanisation: Increases demand for transport, construction and energy.
• Industrial emissions: Certain industries continue to release harmful pollutants
• Agricultural burning: Crop-residue burning contributes to seasonal pollution
• Monitoring gaps: Some regions lack sufficient air-quality monitoring infrastructure.

FAQs