Today’s Image of the Day from NASA Earth Observatory features thick haze over Thailand during the fire season. The photograph was captured on March 16, 2024 by the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi NPP satellite.

Waves of smoke and haze

“Each year in January and February, satellites begin to detect waves of smoke and fire in Southeast Asia, particularly in highland forests in Cambodia, Laos, Myanmar, and Thailand. Fire activity continues to increase through March and April, reaches a peak during the height of the dry season, and then fades in May with the start of the rainy season,” noted NASA.

“Individual fires are usually small and short-lived. But they are often so numerous that smoke, along with air pollution from rural and urban areas, mixes to produce thick layers of haze that blanket the landscape.”

According to NASA, the haze contains mixtures of small airborne particles called aerosols and gaseous pollutants such as nitrogen dioxide, sulfur dioxide, carbon monoxide, and ozone that degrade air quality.

Haze in Thailand 

An international field campaign – the Airborne and Satellite Investigation of Asian Air Quality (ASIA-AQ) – was launched to investigate the haze in Thailand.

“During the last two weeks of March 2024, NASA’s DC-8 and Gulfstream III aircraft flew several flights over Chiang Mai, Bangkok, and rural areas surrounding the cities to sample air quality with several sensors. At the same time, satellites observed the haze from above,” said NASA.

James Crawford, ASIA-AQ’s principal investigator, said the team is collaborating closely with national and local government entities in Thailand.

“The goal is to take as many simultaneous measurements of pollutants as possible from the ground, air, and space,” said Crawford. The team will use the data to gain a better understanding of how the haze forms, evolves chemically over time, and moves throughout the region.

Haze and public health in Thailand

According to media reports, nearly 200,000 people have been hospitalized this year due to air quality in the region, with over 1.3 million people falling ill since January. 

Causes of the haze

The root causes of the haze include agricultural burning, particularly of corn fields, as part of slash-and-burn practices to prepare land for the next planting cycle. This is exacerbated by the dry season when there’s little rain to wash the pollutants away.

The situation is worsened by industrial emissions and vehicle fumes, particularly in urban areas like Bangkok​.

Sustainable solutions are needed

Efforts to address the crisis have been complex, involving local and transboundary issues. Much of the agricultural burning occurs not only within Thailand but also in neighboring countries like Myanmar and Laos, contributing to the transboundary nature of the haze.

Activists and local communities have called for sustainable solutions that do not exacerbate the poverty of smallholder farmers, emphasizing the need for affordable and realistic alternatives to burning​.

Mitigation measures 

The Thai government has implemented a no-burning rule until the end of April to combat wildfires and haze, but enforcement and effectiveness remain challenges​​.

Some measures taken to mitigate the immediate effects of pollution in urban areas include spraying water and seeding clouds to encourage rain, although these have had limited success​​.

This ongoing environmental crisis has sparked widespread concern among citizens, who are increasingly using public interest litigation to hold companies and the government accountable for environmental commitments.

With recent political changes, there is hope that the new administration will take more decisive action against the haze, possibly through more stringent regulations and international cooperation​​.

Health impacts of haze

Haze poses several health hazards for those exposed to it, particularly when it contains fine particulate matter (PM2.5). Here are some of the main health risks associated with exposure to haze:

Respiratory problems

Haze can aggravate conditions such as asthma, bronchitis, and other chronic obstructive pulmonary diseases (COPD). The fine particles can penetrate deep into the lungs, causing inflammation and reducing lung function.

Cardiovascular issues and haze

Exposure to fine particulate matter can also affect the cardiovascular system, leading to increased risk of heart attacks, strokes, and high blood pressure. Particles can affect blood vessel function and promote the formation of blood clots.

Eye irritation

Haze can cause eye irritation, leading to conditions such as conjunctivitis (pink eye) or exacerbated symptoms in people with existing eye conditions.

Skin problems

For some people, exposure to polluted air can cause skin irritation or exacerbate skin conditions like eczema or psoriasis.

Reduced immune function

There is evidence to suggest that prolonged exposure to polluted air can weaken the immune system, making individuals more susceptible to infections.

Impact on mental health

There are growing concerns about the impact of air pollution on mental health, with studies suggesting a link between exposure to polluted air and an increased risk of depression and anxiety.

Pregnant women and children

Pregnant women, children, and the elderly are particularly vulnerable to the effects of haze. There may be increased risks of preterm birth and low birth weight in babies, and children may experience delayed development and reduced lung function.

The health impacts of haze can be mitigated by staying indoors on days when air quality is particularly poor, using air purifiers, wearing masks designed to filter out fine particles, and following local health advisories.

Image Credit: NASA Earth Observatory

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