Chiang Mai's Air Pollution: The Haze Over Paradise

Chiang Mai, Thailand, has been ranked as the world's most polluted city, with hazardous levels of air pollution about nine out of twelve months of the year. The air quality index (AQI) in Chiang Mai has been recorded at 188, falling under the “unhealthy” category. The city's air pollution is mainly attributed to the burning of agricultural biomass during the harvest season, with particles known as secondary aerosols from field fires in stagnant air accounting for a significant portion of the haze. The high levels of PM2.5 in the air, which can penetrate deep into the lungs and cause respiratory issues, have led to thousands of people seeking treatment in hospitals. Despite the severity of the problem, the government's response has been lacklustre, with ineffective attempts to spray water into the air and seed clouds to induce rain.

The role of agricultural biomass burning in Chiang Mai's air pollution

Chiang Mai, Thailand, is known for its poor air quality, which is largely due to agricultural biomass burning. This practice is common in the developing world, especially in South-East Asia, where it is used as a cost-effective way to control crop residues and weeds before and after cultivation. The burning of agricultural residues, especially in the highlands where maize is grown for animal feed, has been identified as a major source of particulate pollution in Chiang Mai.

The burning of crop residues, such as maize, releases particulate matter (PM2.5) into the air, which can have negative health effects. These particles are small enough to be deposited in the pulmonary region, and their large surface area allows them to absorb toxins such as polycyclic aromatic hydrocarbons (PAHs) and heavy metals. This can trigger or worsen respiratory conditions such as asthma, emphysema, bronchitis, silicosis, and lung cancer.

The Pollution Control Department (PCD) has reported that open biomass burning in agricultural and forest areas in northern Thailand produces a vast amount of smoke and haze during the dry season (February to April). This smoke accumulates in the valleys and river basins of Northern Thailand, impacting remote areas far from major cities. The effects of this smoke are not limited to Thailand, as about 23% of the haze is attributed to long-range pollution, likely from India.

The burning season in Chiang Mai is influenced by a combination of biomass burning and meteorological conditions. The dry season, with low rainfall, provides ideal conditions for more intense fires. The timing of crop residue burning also plays a role, with most farmers burning maize residues during April and May, contributing to the high levels of air pollution during these months.

To address the air pollution crisis, Thailand has implemented policies such as the national zero-burning directive in 2013. However, these measures have had limited success, as people often burn before and after the ban periods, prolonging the haze season. As a result, Chiang Mai province has adopted a permit system for controlled burns, utilising the FireD app to predict pollution levels and make informed decisions.

The health implications of Chiang Mai's air pollution

The air quality in Chiang Mai is a concern for residents and visitors alike, with potential health implications for all. The city's overall air quality index has been recorded at 71, which is considered moderate. While this level is acceptable for most people, certain pollutants may be harmful to sensitive individuals.

The air pollution in Chiang Mai is characterised by fine particulate matter (PM2.5), with an AQI of 71, and respirable particulate matter (PM10), with an AQI of 82. These particles can be inhaled and cause respiratory issues. Nitrogen dioxide (NO2) is also present, with an AQI of 8, which can irritate the lungs and worsen respiratory conditions. Sulfur dioxide (SO2) and ozone (O3) levels are lower, with AQIs of 1 and 15 respectively, but still contribute to the overall poor air quality.

The health implications of air pollution in Chiang Mai can include respiratory problems, such as asthma symptoms like wheezing, shortness of breath, chest tightness, and persistent cough. Prolonged exposure to poor air quality can also increase the risk of developing respiratory infections and other respiratory diseases.

Additionally, air pollution can have cardiovascular effects, as fine particulate matter can enter the bloodstream and affect the heart and blood vessels. This can lead to an increased risk of heart disease, high blood pressure, and other cardiovascular issues.

To mitigate the health risks associated with air pollution, residents and visitors of Chiang Mai are advised to monitor the real-time air quality data and take appropriate precautions. This may include limiting outdoor activities when the AQI is poor, using air purifiers indoors, and seeking medical advice if experiencing any respiratory or cardiovascular symptoms.

The Thai government's response to the issue

The Thai government has faced criticism for its response to Chiang Mai's air pollution crisis. In March 2024, Prime Minister Srettha Thavisin declined to declare the northern city a disaster area, citing concerns over the potential impact on the country's recovering tourism industry. This decision was criticised as being more focused on optics and short-term economic gains than on the health and well-being of Thai citizens.

The government's inaction has been called out by various groups, including retired senior tourists, who threatened to stay away from Chiang Mai until the smog problem was addressed, and 1,700 plaintiffs in northern Thailand who filed a lawsuit against the government for inaction and human rights violations. The Tourism Council of Chiang Mai also urged the government to take action, warning that the city's reputation as a tourist destination was being damaged by its air quality problems.

While the Thai government has not declared a disaster zone, which would have provided emergency funds for mitigation, it could still address the issue through broader national solutions. This includes expanding carbon markets, imposing higher carbon costs on emissions, implementing emission-trading schemes, and taxing strong polluters such as large agribusinesses.

Some steps have been taken to address air pollution in Thailand. For example, the Thai Meteorological Department has provided meteorological data for research on the dynamics of influenza and pneumonia incidences in Chiang Mai due to air pollution. However, there is still a lack of leadership and comprehensive solutions to effectively tackle the issue.

The impact of neighbouring countries

Chiang Mai, a city in northern Thailand, is a popular tourist destination. However, it faces seasonal spikes in air pollution, with haze accumulating in the Ping River valley and other valleys in the region. During the dry months of March and April, levels of airborne particulate matter increase significantly. This is due to smoke from crop fires in the valleys and forest fires in the surrounding mountains, which mix with urban emissions from traffic, industry, and other sources.

Large agribusinesses, such as Charoen Pokphand and its subsidiary CP Foods, have also been implicated in the air pollution issue. While they are not directly burning any fields, their expansion of contract farming in Thailand and neighbouring countries has been cited as a contributing factor to the problem.

The Thai government has been criticised for not doing enough to address the air pollution crisis in Chiang Mai and northern Thailand. Weenarin Lulitanonda, co-founder of the Thailand Clean Air Network, has stated that the air quality in the region is cutting people's lives short by several years and causing various health issues. She has been trying to rally the Thai public and pressure the government to take more action on what has become one of the region's most severe environmental disasters.

The social and economic factors contributing to the problem

Chiang Mai, Thailand, has been ranked as the world's most polluted city, with hazardous levels of air pollution about nine out of twelve months of the year. The air pollution in Chiang Mai is caused by a combination of social and economic factors, which have led to a lack of action from the government and local authorities.

One significant social factor is the influence of powerful agricultural businesses and tycoon families on the government. The burning of agricultural biomass, including sugarcane, maize, and rice fields by farmers during the harvest season, contributes to the haze and smog in the region. However, the government has been reluctant to address this issue due to its ties with the agricultural industry and the involvement of economically powerful families.

Another social factor is the scapegoating of farmers, hill tribes, and neighbouring countries such as Myanmar and Laos. While the burning of fields in these regions contributes to the air pollution in Chiang Mai, it is essential to recognise that the problem is multifaceted and requires a comprehensive approach.

The economic dependence on agriculture in the region may also contribute to the problem. With harvest seasons falling during the dry season, when neither wind nor rain can disperse the haze, farmers rely on controlled fires to remove undergrowth and fertilise their fields. This practice, while detrimental to air quality, is deeply rooted in the economic activities of the region.

Additionally, the passive attitude towards the issue among the Thai public has hindered progress. Weenarin Lulitanonda, a former World Bank economist and co-founder of the Thailand Clean Air Network NGO, has been trying to raise awareness and rally support to address the problem. However, there is a general sense of passivity, with many individuals and families accepting the situation rather than actively advocating for change.

Furthermore, the lack of effective solutions implemented by the authorities indicates a potential economic constraint or misallocation of resources. While attempts to spray water into the air and seed clouds to induce rain have been made, these measures have had a lacklustre effect. This suggests that either the necessary resources for more effective solutions are not available or that the allocated resources are not being utilised efficiently.

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