NEW DELHI: India is the sixth most-polluted country, when it comes to levels of fine particulate matter, a major air pollutant, according to the 2025 World Air Quality Report by IQAIR, a Swiss air quality technology company. While Pakistan is the most polluted country in 2025, China is in the 20th position.
All of the world's 25 most polluted cities are located in India, Pakistan, and China, with India being home to three of the four most polluted cities. Notably, five Indian cities, including New Delhi, are among the top ten most polluted cities.
IQ Air is a Swiss company that monitors air pollution globally from over 80,000 data points in around 10,000 cities across 143 countries, and releases annual rankings on air quality.
According to their report, wildfires, exacerbated by climate change, significantly contributed to the degradation of global air quality in 2025.
The report identifies Loni, in Ghaziabad, as the most polluted city in the world, with a PM2.5 concentration of 112.5 µg/m³, which represents a nearly 23% increase from the previous year. This is followed by the Chinese city Hotan.
Other Indian cities in the top ten list include Byrnihat, New Delhi, Ghaziabad, and Ula, while the remaining four cities are from Pakistan. These areas consistently experience unbreathable air quality throughout the year, with PM2.5 concentrations exceeding the World Health Organisation's (WHO) average limits by 5 to 10 times.
The WHO recommends an annual average limit of 5 µg/m³ for PM2.5, whereas India's National Ambient Air Quality Standards (NAAQS) set the limit at 40 µg/m³. PM2.5 refers to fine inhalable particulate matter that is about 30 times thinner than a human hair and can penetrate deep into the lungs and bloodstream, leading to serious health issues.
In terms of country rankings, India stands sixth with an average annual PM2.5 concentration of 48.9 µg/m³, an improvement from 72.5 µg/m³ in 2018. China holds the 20th rank, with a PM2.5 concentration of 29.6 µg/m³, reduced from 41.2 µg/m³ in 2018. Pakistan ranks at the top with a PM2.5 concentration of 67.3 µg/m³. The top 20 list consists solely of countries from Asia and Africa.
Nieuwoudtville in South Africa was recognised as the world’s cleanest city, with an annual average PM2.5 concentration of 1.0 µg/m³.
The report indicates that global progress on air quality is stalling, as wildfire smoke and climate change continue to exacerbate pollution levels. Compared to the previous year, 54 countries saw increases in their annual average PM2.5 levels, 75 countries experienced declines, two remained unchanged, and 12 were newly represented in this year's dataset.
According to the data, 130 out of 143 countries/territories (91%) surpassed the WHO annual average PM2.5 guideline value. Only 14% of global cities met the WHO annual average, a decrease from 17% the previous year.
The five most polluted countries are Pakistan (67.3 µg/m³), Bangladesh (66.1 µg/m³), Tajikistan (57.3 µg/m³), Chad (53.6 µg/m³), and the Democratic Republic of the Congo (50.2 µg/m³). 2025 marked the second consecutive year without any cities in East Asia meeting the WHO PM2.5 guidelines. Pollution patterns in China also show a westward shift in elevated concentrations.