The 2025 World Air Quality Report indicates signs of progress despite the ongoing global struggle with air pollution. Some of Asia’s biggest cities reduced their PM2.5 concentrations in 2025 when compared to 2024. However, those improvements are still far from sufficient. Three of the five cities on this list continue to consistently experience air quality levels classified as very unhealthy to hazardous.
Millions of residents in these major cities still face elevated health risks from long-term exposure to airborne pollutants like PM2.5 – tiny particulate matter measuring less than 2.5 microns in diameter. Vulnerable populations, such as children, the elderly, and those with pre-existing conditions like asthma or heart disease, bear the brunt of this burden. Though there is much more progress to be made, any improvement in air quality is a step in the right direction towards achieving safe and breathable air for all.
5. Ulaanbaatar, Mongolia
Ulaanbaatar reduced its average annual PM2.5 concentration from 25.7 µg/m³ in 2024 to 17.9 µg/m³ in 2025, an improvement of 7.8 µg/m³.
The decreased PM2.5 levels is a step in the right direction towards healthy breathing, but Ulaanbaatar’s air quality still does not reach the World Health Organization’s safe concentration level guideline of 5 µg/m³ (1).
Diesel fuels and coal burning are common resources for resident heating and vehicle operations in Ulaanbaatar, creating an abundance of airborne pollutants. Especially in the colder winter months, added coal burning and temperature inversions trap large amounts of pollutants close to the ground, elevating PM2.5 concentrations.
Air quality in Ulaanbaatar, Mongolia on June 25, 2026. Source: IQAir.
In 2019, the Mongolian Government enacted a ban against raw coal utilization for domestic heating (2). Long-term clean air solutions depend on resources that provide sustainable fuel and healthy utilization with low respiratory risks.
4. Chiang Mai, Thailand
Chiang Mai saw its average annual PM2.5 concentration drop from 26.4 µg/m³ in 2024 to 18.2 µg/m³ in 2025, marking an 8.2 µg/m³ improvement.
The shift in PM2.5 levels is a notable improvement for the northern Thai city, inching closer to safe air quality levels for all. However, Chiang Mai maintains a moderate air quality index, which may depend on clean fuel and agricultural resources to reach low-risk PM2.5 concentrations.
Air quality in Chiang Mai, Thailand on June 25, 2026. Source: IQAir.
Chiang Mai experiences fluctuating air quality conditions and seasonal pollutants bursts, particularly during the dry season. Cultural crop burnings are the most prevalent in Chiang Mai, causing mass production of volatile organic compounds (VOCs) and particulate matter across the city within the warmer months.
Communities and residents in Thailand have pushed for systemic change within the air quality landscape, introducing a Clean Air Bill and non-profit initiatives (3).
3. Delhi, India
Delhi, one of the world’s most polluted cities, was able to lower its average annual PM2.5 concentration from 108.3 µg/m³ in 2024 to 99.6 µg/m³ in 2025, an improvement of 8.7 µg/m³.
While the reduced PM2.5 levels are an impactful step towards safe breathing conditions, Delhi’s air quality index remains in the unhealthy range, and airborne pollutants could still invade indoor spaces.
Air quality in Delhi, India on June 25, 2026. Source: IQAir.
Delhi, a populous urban city, experiences a complex mix of airborne pollutants and harmful particulate matter year-round, including construction dust, cultural crop burnings, and industrial emissions. Traffic pollution and gases are among the most prevalent pollutants in India, contributing to about 11% of air pollutant-related deaths in the country (4).
In 2026, Delhi reformed traffic policies and promoted incentives for residents to switch to electric-powered vehicles (5)(6). However, long-term systemic shifts in fuel utilization and energy sources hold the potential to extend air quality improvements.
2. Dhaka, Bangladesh
Dhaka reduced its average annual PM2.5 concentration from 78 µg/m³ in 2024 to 68 µg/m³ in 2025, achieving a 10 µg/m³ improvement.
Dhaka has maintained unhealthy AQI levels since the first World Air Quality Report in 2017, but the city has reached its most improved PM2.5 concentrations in 2025. Despite the improved air quality conditions and decreased PM2.5 exposure, the city’s air remains at an unhealthy AQI level, creating a harmful breathing environment for sensitive populations.
Dhaka faces numerous air pollution concerns derived from busy highways and high-production factories, including abundant traffic emissions, particulate matter from construction sites, and industrial smoke. As a country, Bangladesh established a National Air Quality Management Plan for 2024-2030, focused on reducing PM2.5 concentrations and decreasing pollutant production nationwide. For long-term air quality improvement, limiting brick kilns and harmful cooking sources is key, as these pollutants have been linked to elevated respiratory health risks and the production of over 200 volatile organic compounds (7).
Air quality in Dhaka, Bangladesh on June 25, 2026. Source: IQAir.
1. Lahore, Pakistan
Lahore achieved the most significant improvement among the top five major cities. The city reduced its average annual PM2.5 concentration from 102.1 µg/m³ in 2024 to 88.9 µg/m³ in 2025, a 13.2 µg/m³ drop.
Air quality in Lahore, Pakistan on June 25, 2026. Source: IQAir.
While a positive development, this progress needs to be weighed in context with another fact: Lahore’s air quality has been in the hazardous range since the first World Air Quality Report in 2017, and it was ranked the second most polluted major city in the world in 2025.
The city’s pollution is driven by a combination of factors, including vehicular emissions from an aging fleet, industrial activity, dust from construction, and seasonal crop burning in Punjab Province. While the Pakistani government has introduced measures such as smog alerts, temporary school closures, and restrictions on certain industrial activities during high-pollution periods, seasonal air quality issues persist. The health impact is clear: 68% of Pakistanis reported smog-related health issues in a survey conducted in 2024. 84% of respondents living in Lahore noted they had experienced respiratory illnesses (8).
Pathways to cleaner air
While the improvements in these cities are a step in the right direction, mitigating persistent poor air quality requires sustained action. Here’s how progress can be accelerated:
What governments can do
- Strengthen and enforce air quality standards to hold industries and vehicles accountable for their emissions.
- Invest in renewable energy and public transportation to reduce reliance on fossil fuels and private vehicles.
- Expand air quality monitoring networks to provide real-time data and inform targeted interventions.
- Promote regional cooperation to address transboundary pollution, such as crop burning and industrial emissions that cross borders.
What communities can do
- Support and participate in local initiatives to raise awareness about air pollution and its health impacts.
- Advocate for stronger policies and better enforcement to protect vulnerable populations.
What individuals can do
- Choose sustainable transportation options, such as walking, cycling, or using public transit, to reduce personal contributions to air pollution.
- Use air purifiers and wear high-quality masks on high-pollution days to limit exposure.
- Stay informed about real-time air quality data to make healthier daily decisions.
Conclusion
Air quality improvement in these five Asian cities offers hope in the ongoing fight for clean air. However, the fact that three of these cities—Delhi, Dhaka, and Lahore—still have air quality levels classified as unhealthy to hazardous underscores the long journey towards clean air quality.
It’s true that millions of people in these cities and around the world continue to breathe air that is far from safe. Yet progress shown in 2025 can serve as a foundation for bolder, more ambitious action to ensure that clean air becomes a reality for all.
