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In a grim update on the global air pollution front, Delhi has once again been declared the world’s most polluted capital city, according to IQAir’s 2024 World Air Quality Report. But while the Indian capital continues to choke under toxic air, the industrial town of Byrnihat in Meghalaya shocked researchers by emerging as the world’s most polluted metropolitan area, with a PM2.5 concentration over 25 times above safe limits. Based on data from over 40,000 monitoring stations across 138 countries, the report lays bare the escalating air quality crisis — and India’s prominent place within it.
India Slips to 5th Spot, But Breaches WHO Limits by Tenfold
India dropped from being the third most polluted country in 2023 to fifth in 2024; this slight dip in rank does not reflect any real improvement in air quality. Its air remains dangerously unsafe. The country recorded an average PM2.5 concentration of 50.6 µg/m³, more than ten times higher than the WHO’s five µg/m³ annual safe limit. This decline in ranking doesn’t reflect an improvement in Indian air quality—instead, it’s a sign that air pollution worsened in other countries.
The top five most polluted countries in 2024 were:
- Chad: 91.8 µg/m³ (18 times higher than WHO limit)
- Bangladesh: 78.0 µg/m³
- Pakistan: 73.7 µg/m³
- Democratic Republic of the Congo: 58.2 µg/m³
- India: 50.6 µg/m³
What’s more alarming is that 91.3% of all monitored countries (126 out of 138) exceeded the WHO’s recommended annual PM2.5 limit. Only seven countries — including Australia, Estonia, and New Zealand — met the clean air benchmark. That means only 17% of global cities had air deemed safe by WHO standards in 2024.
Delhi: Still the World’s Most Polluted Capital
Despite new measures and court interventions, Delhi retained its title as the world’s most polluted capital for another year. With an annual PM2.5 average of 92.7 µg/m³, the city’s air is nearly 19 times more polluted than what’s considered safe. The top polluted capitals following Delhi include Dhaka (80.2 µg/m³) and N’Djamena, Chad, cementing South Asia and parts of Africa as air pollution hotspots.
Despite emergency measures like the Graded Response Action Plan (GRAP) and anti-stubble-burning campaigns, Delhi’s air continues deteriorating. Experts point out that the capital suffers from year-round pollution, driven by a deadly mix of industrial emissions, vehicular exhaust, dust from construction, and burning seasonal crop residue.
Byrnihat: From Industrial Cluster to Pollution Epicentre
The town of Byrnihat in Meghalaya, near the Assam border, emerged as the most polluted metropolitan area in 2024. It recorded an average PM2.5 level of 128.2 µg/m³., which is not only the highest in India but also globally, surpassing even traditionally notorious cities like Lahore, Hotan, and New Delhi.
Cement plants, unregulated industrial activities, coal-based factories, and continuous heavy truck traffic primarily contribute to the pollution in Byrnihat. Many of these operations function without essential pollution control devices, significantly worsening air quality. CFC’s recent coverage highlighted growing health concerns among residents, including chronic respiratory issues and rising asthma cases. A follow-up report covered how the Meghalaya Pollution Control Board shut down six factories over serious environmental violations and public health risks.
Byrnihat’s ranking shows that India’s pollution problem is no longer restricted to major cities — smaller industrial towns are increasingly becoming unmonitored toxic hotspots.
The World’s Dirtiest and Cleanest Cities in 2024
According to the IQAir report, Central and South Asia dominate the list of the world’s most polluted cities, with India accounting for six of the top nine most polluted urban areas. The region also hosts all of the top seven most polluted cities worldwide. Notable names on the polluted leaderboard include:
- Byrnihat (India) – 128.2 µg/m³
- Begusarai, Guwahati, Patna, Muzaffarpur, Darbhanga (India)
- Lahore (Pakistan)
On the other end of the spectrum, Mayagüez in Puerto Rico emerged as the cleanest metropolitan area, with an average PM2.5 reading of just 1.1 µg/m³. Meanwhile, Kohima (Nagaland) was noted as India’s cleanest city, with a reading of 11.6 µg/m³, a sharp contrast to heavily industrialised areas.
Ontario (California) was the most polluted city in the United States, while Seattle (Washington) was the cleanest major city.
Global Trends and Regional Gaps in Air Monitoring
The 2024 report also concerns data inequality. For example, in Africa, there is only one air quality monitoring station per 3.7 million people. This severe lack of data infrastructure makes tracking real-time pollution and health risks in several parts of the world difficult.
Meanwhile, Southeast Asian countries saw slight improvements in PM2.5 levels, thanks to favorable weather patterns and stricter local controls. However, transboundary haze and El Niño-driven wildfires — particularly in Brazil’s Amazon, where pollution quadrupled in September — remain serious challenges.
Oceania remains the world’s cleanest region, with 57% of its cities meeting WHO air quality standards, led by countries like Australia and New Zealand.
Policy Gaps, Public Health Threats, and the Urgent Call for Action
India’s repeated appearance at the top of global pollution rankings isn’t just a statistical concern — it’s a public health emergency. Long-term exposure to PM2.5 is linked to respiratory disorders, heart diseases, neurological impacts, and reduced life expectancy. Children, the elderly, and those with pre-existing conditions are especially vulnerable.
Yet, most policies remain reactive. While efforts like the National Clean Air Programme (NCAP) exist on paper, experts argue they lack consistent funding, cross-departmental execution, and strict enforcement. From Delhi’s smog-choked skyline to Byrnihat’s unseen industrial emissions, the 2024 IQAir report shows that air pollution is not just an urban problem—it’s a growing national and global emergency. Only 17% of cities globally meet the WHO’s clean air criteria, and 91% of countries exceed safe limits. The scale of the crisis is undeniable.
India’s fight for breathable air must shift from high-profile cleanups to systemic change, especially in under-monitored regions like the Northeast. Because until every citizen — from Delhi to Byrnihat — can breathe safe air, the battle is far from won.
References:
https://www.iqair.com/in-en/world-air-quality-report
https://indianexpress.com/article/cities/delhi/delhi-world-most-polluted-capital-9880298
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Photo by Ravi Sharma on Unsplash
