Air pollution is one of the greatest environmental challenges facing the world today. Bangkok is one of the top five on the list of cities with the worst air quality where once Beijing was listed. However, Beijing has implemented a series of measures to reduce PM2.5 pollution and improve air quality.
PM2.5 refers to fine particulate matter, which consists of tiny particles, 2.5 micrometres or less in diameter. These particles are so small that they can penetrate deep into the lungs and bloodstream. For the past several years, efforts involving a combination of regulatory, technological and policy-driven approaches have been ongoing.
According to the UNEP (United Nations Environment Programme) the sources of PM2.5, including burning fossil fuels; vehicle emissions; industrial activities; wildfires and indoor sources such as smoking and cooking with gas or wood. The exposure to PM2.5 can have a range of adverse health effects, including respiratory problems such as asthma, bronchitis and chronic obstructive pulmonary disease (COPD); lung cancer; heart disease; strokes; premature birth and low birth weight.
In 1998, Beijing declared war on air pollution. The challenge was to find ways to improve air quality in one of the largest and fastest growing cities in the developing world. Since then, air quality has improved substantially, and the lessons learned provide a roadmap for other cities tackling air pollution. According to a UNEP report, Beijing has implemented a "coal-to-gas" policy since 2005 and reduced coal combustion by nearly 11 million tonnes by 2017. High-efficiency terminal treatment facilities were continuously renovated, and ultra low emission standards were enforced during this period.
In a report of the Climate & Clean Air Coalition.org, Beijing implemented, Vehicle Emission Controls, which include stricter Vehicle Emission Standards, including the adoption of the China VI standard, which is equivalent to Euro 6. The government has also promoted the public to use electric vehicles (EVs) and hybrids (HEVs) through subsidies, tax incentives and the expansion of charging infrastructure. Motorcycles powered by gasoline are prohibited in Beijing; only electric motorcycles are allowed.
There are ongoing projects to expand and develop eco-friendly public transportation systems such as electric trams, electric buses and high-speed trains, to provide affordable services for the public to reduce private cars on the street. These services are accessible and affordable to everyone, regardless of their profession or economic status, ensuring convenience without financial burden. The cost is approximately 3-6 yuan for a 32-kilometer distance, or around 15-30 Thai baht.
In addition, Beijing has implemented traffic control measures, like odd-even license plate restrictions, to reduce the number of vehicles on the road during high-pollution days. Moreover, the city has undertaken large-scale tree planting campaigns to increase green spaces, which help absorb pollutants and improve air quality. The city has developed green belts and parks to act as natural air filters. Furthermore, the city has established a comprehensive air quality monitoring network to track PM2.5 levels and other pollutants in real time. The city issues air quality alerts and health advisories to inform the public during high-pollution days, encouraging people to take protective measures, and most importantly, they have implemented strict enforcement and penalties. Regular inspections are conducted to ensure compliance with environmental regulations. Companies and individuals that violate air pollution regulations face significant fines and penalties.
Moreover, the government has relocated or shut down heavily polluting industries around the city such as coal-fired power plants, steel mills, and cement factories, to reduce emissions.
These measures have led to significant improvements in Beijing's air quality. PM2.5 levels have decreased substantially since 2013, when the city declared its "war on pollution".
However, challenges remain, and Beijing continues to work on further reducing pollution to meet national and international air quality standards, set by the Environmental Protection Agency (EPA). The annual average concentration of PM2.5 should be no higher than 12 micrograms per cubic metre (µg/m3), and the city encourages the public to avoid burning fuels indoors, use public transportation or walk when possible, limit driving time, use an air purifier at home and wear a mask when outdoor air quality is poor. By the end of 2017 fine particulate pollution (PM2.5) in Beijing fell by 35% and by 25% in the surrounding Beijing-Tianjin-Hebei region.
A review of 20 years’ air pollution control in Beijing was compiled by a UN-led environment team of international and Chinese experts over two years, covering between 1998 through 2017.
In it, Joyce Msuya, Acting Executive Director of the UN Environment Programme, said, “This improvement in air quality didn’t happen by accident. It was the result of an enormous investment of time, resources and political will. Understanding Beijing’s air pollution story is crucial for any nation, district or municipality that wishes to follow a similar path.”
Meanwhile, Bangkok Post reported last month that Bangkok was ranked as the fourth worst city in the world for air quality, according to the latest data from Swiss-based IQAir, as toxic haze continues to affect the capital and other provinces in the country. The air quality index in Bangkok had reached as high as 188.
The Environmental Health Perspective (EHP) recently reported that particulate matter < 10 μm in aerodynamic diameter is the most hazardous air pollutant in urban and rural areas. In cities such as Bangkok, air quality monitoring performed by the Pollution Control Department (PCD) for the past 10 years has revealed that the levels of PM2.5 have exceeded both annual national standards, primarily because of vehicular emissions.
In the past month, the Bangkok Metropolitan Administration (BMA) has declared 48 of its 50 districts as red (hazardous-to-health) zones, with particulate matter 2.5 micrometres or less in diameter, averaging 88.4 micrograms per cubic metre (µg/m³). In January 2025, all 50 districts in Bangkok reported red, hazardous-to-health levels of PM2.5. In 2024, Bangkok had only 43 days of "good air quality".
Hence, before it’s too late, Bangkok and Chiang Mai’s administrations, in particular, should seriously implement policies similar to Beijing’s to tackle air pollution successfully.
