What pollutes Indian cities?

India faces voluminous air quality challenges. It alone accounts for six of the nine most polluted cities, with pollution sources including vehicular emissions, industrial discharges, construction dust, and crop residue burning. A recent report indicates that only 17 percent of the world’s cities meet air pollution guidelines, with countries like Chad, Congo, Bangladesh, Pakistan, and India having the dirtiest air. 

Air pollution remains an environmental threat to human health. According to the World Health Organization (WHO), 99 percent of the global population lives in areas that do not meet recommended air quality guideline levels.1 Air pollution is the second leading global risk factor for death and the second leading risk factor for deaths among children under five, following malnutrition, due to its significant impact on respiratory and developmental health

The World Air Quality Report evaluates the global state of air quality for 2024. This comprehensive report presents PM2.5 air quality data collected from 8,954 cities across 138 countries, regions, and territories. The data was sourced from over 40,000 regulatory air quality monitoring stations and low-cost sensors.

The National Capital Region (NCR) topped the rankings, with New Delhi, Greater Noida, Noida, Ghaziabad, Faridabad, and Gurgaon securing the top six spots.

PM 2.5

The PM2.5 data is measured in micrograms per cubic meter (μg/m³) and is visualised as a function of the World Health Organization (WHO) annual PM2.5 air quality guidelines. PM2.5 refers to tiny particles with 2.5 micrometres or less diameters that can go deep into the lungs and even enter the bloodstream. The combustion of gasoline and oil is linked to premature death, heart attacks and breathing difficulties. Though the World Health Organization recommends that average annual concentrations of PM2.5 should not exceed 5 micrograms per cubic meter, only 17% of cities worldwide meet its air quality standard, the report said.

India, the world’s most populous country, with more than 1.4 billion people, had a 7 percent decline in PM2.5 concentration last year. Air pollution remains a “significant health burden” that reduces life expectancy there by an estimated 5.2 years, the report said. The nation’s Major pollution sources include industrial discharge, construction dust and crop residue burning. Air quality in Pakistan reached “hazardous” levels because of a combination of festival celebrations, brick kiln emissions and adverse weather.

According to a study, six of the world’s 10 most polluted cities are in India, while California has the worst air pollution in North America. India ranked 5th in air quality worldwide, with Delhi being the most polluted capital, according to the World Air Quality Report 2024. The PM2.5 concentration in India is ten times higher than WHO pollution guidelines, and only 17% of global cities meet these standards.

Overall, 35% of Indian cities reported annual PM2.5 averages exceeding ten times the WHO guideline. Agra near Delhi was so polluted with a thick layer of toxic smog that it prevented tourists from snapping selfies at the Taj Mahal. India ranked fifth globally with an average PM2.5 concentration of 50.6 μg/m³, slightly better than its neighbours—Bangladesh. which ranked second with 78.0 μg/m³, and Pakistan, which ranked third with 73.7 μg/m³. All three fall under the maroon category, where PM2.5 levels exceed WHO guidelines by over ten times the 5 μg/m³ limit.

New Delhi was the most polluted capital city globally with an average PM2.5 concentration of 91.8 μg/m³, followed by N’Djamena, the capital of Chad, a country in central Africa with the world’s worst air pollution, according to the 2024 World Air Quality Report released by IQAir, a Swiss air monitoring company. Chad’s PM2.5 levels were more than 18 times higher than the WHO guideline, with mineral dust in the Sahara Desert as the primary source of air pollutants.

Global scenario

Only 12 countries, regions, and territories recorded PM2.5 concentrations below the WHO annual PM2.5 guideline of 5.0 μg/m³, most of which were in the Latin America and Caribbean or Oceania region; however, in 2024, 17% of cities included in the report met the WHO annual PM2.5 guideline level, up from 9% in 2023.

China, the world’s biggest emitter of greenhouse gases, recorded lower air pollution levels in more than 300 cities in 2024. Oceania, which includes Australia, New Zealand and Pacific island nations, is the world’s cleanest region, with 57% of cities meeting the WHO standard. The report said ten of the 15 most polluted cities in North America, including Ontario and Bloomington, are in California as the United States reclaimed the top spot as the most polluted country in the region in 2024.

IQAir’s global chief executive, Frank Hammes observes, “Air pollution remains a critical threat to both human health and environmental stability, yet vast populations remain unaware of their exposure levels. Air quality data saves lives. It creates much-needed awareness, informs policy decisions, guides public health interventions, and empowers communities to take action to reduce air pollution and protect future generations.”

The report also noted the “considerable” gaps in air quality that still exist in many parts of the world. According to IQAir estimates, only 21% of the world’s population has access to hyperlocal, real-time air quality information.

The air we breathe indoors can be up to five times more polluted than outdoor air, as studies by environmental health agencies suggest. Nitin Naik said that India’s rapid urbanisation is fueling infrastructure growth but also exacerbates air pollution—six of the world’s ten most polluted cities are in India. This poses significant challenges for improving indoor environments, especially in tropical climates where heat and humidity demand constant cooling. Balancing cooling, ventilation, filtration, and energy efficiency is complex, as outdoor air is often heavily polluted, making it difficult to ensure healthy indoor spaces whilst still maintaining thermal comfort & sustainability.

Poor indoor air quality (IAQ) is often the result of various factors, making the Right climate control solutions not just a luxury but a necessity, notes Jody Heathirector, Advanced Climate Technical Services Ltd.

Reducing air pollution

According to the WHO, air pollution accounted for 8.1 million deaths worldwide in 2021. Children under age 5 are considered especially vulnerable, with health effects including premature birth, low birth weight, asthma and lung disease. Addressing air pollution, the second highest risk factor for noncommunicable diseases, is key to protecting public health.

In today’s workplaces, maintaining a comfortable and healthy indoor environment is more necessary than ever. Poor indoor air quality can reduce productivity, discomfort and long-term health problems. Efforts to combat pollution might include temporary measures like restricting vehicle usage, halting construction, and closing schools during peak pollution.

With rising energy costs and increasing awareness of indoor air quality, businesses must adopt smarter climate control solutions to deal with outdoor pollution. It might create a healthier workplace, improved performance, and a more sustainable future.

Most sources of outdoor air pollution are well beyond the control of individuals, and this demands concerted action by local, national, and regional policy-makers working in sectors like energy, transport, waste management, urban planning, and agriculture.

Nitin Naik, Founder & Managing PartnerFounder & Managing Partner, Dew Point

Balancing cooling, ventilation, filtration, and energy efficiency presents a challenge, specifically in environments with compromised outdoor air quality due to high pollution levels.

Jody Heath, Director, Advanced Climate Technical Services Ltd.

The air we breathe indoors can be five times more polluted than outdoor air, so investing in the Right climate control solutions is not just a luxury—it’s a necessity.