Asia dominates the list of world’s most polluted countries, with Bangladesh, Pakistan, India, Indonesia, China, Vietnam, Sri Lanka, and Thailand among the top 25, according to the recently released 2018 World Air Quality Report.

This unwanted distinction for Asia carries implications for tourism, as travelers and industry workers pay closer attention to pollution levels.

Delhi took the cake as the world’s most polluted capital city in 2018. In Southeast Asia, the capitals Jakarta and Hanoi, are worst, with a number of Thai cities also rank high. In fact, Chiang Mai, one of the most visited cities in Thailand, had the dubious honor of beating Delhi for a period in March this year, when seasonal open burning produced the worst pollution in memory the city had ever seen.

Open burning, where land is burned to provide a richer nutrient environment for future crops, is a huge source of pollution in Southeast Asia, particularly in Indonesia. In 2015, it sparked the worst “haze crisis” since 1997 through transboundary air pollution across neighboring countries, premature deaths, flaming diplomatic tensions, and crippling tourism arrivals growth.

Thailand’s Chiang Mai is still suffering from the effects of open burning this year, which lasts from February to April. “This has continued, year after year for the last 10 years at least, with no improvements. And this year is the worst I’ve experienced,” said a retired travel industry veteran residing in Chiang Mai for over 20 years.

“Whole mountainsides are set alight. The forest carpet and the dry leaves emit massive volumes of toxic smoke. Smoldering then continues for days. And it is not restricted to Chiang Mai or Chiang Rai provinces,” said the Chiang Mai industry veteran. “A few years ago I drove the 300 kilometers from Chiang Mai to Nan, and did not see a single patch of unburned forest, except obviously in national parks. Basically, the whole of Northern Thailand burns. Small animals, insects, young trees, and plants at ground level are destroyed. The progressive year-after-year eco-damage is incalculable.

In urban areas, transportation and industry are among the leading culprits, with high numbers of small vehicles such as motorbikes, said IQAir AirVisual. “There is strong correlation between urbanisation and air pollution in [Southeast Asia]: Jakarta and Hanoi have the highest recorded air pollution in the region and are also among the most populated cities.”

In south Asia, apart from open-crop and biomass burning, common culprits of pollution include vehicle exhaust, industrial emissions, and coal combustion, said IQAir AirVisual.

With tourists increasingly demanding quality experiences, industry players such as Dipak Deva are exasperated. Deva, the managing director of Sita Travels, Travel Corporation India, and Distant Frontiers, said, “We have a big mess.”

Like India, there have been “virtually zero effective measures” put in place in either Bangkok or Chiang Mai by local authorities and the national government, said Asian Trails Thailand’s managing director Yves Van Kerrebroeck.

“We as individuals and companies have little power over this; it is an issue of enforcement and political motivation. Hopefully things will change now after the election. We sincerely hope the government will take this seriously and make safe environment a top priority going forward. The air we breathe doesn’t discriminate between rich and poor or political preference,” he said.