Thailand's prime minister once remarked that Bangkok would be heaven on Earth if it were not for the traffic. The people who live here will tell you their city is rapidly becoming more and more like hell.
Air pollution in traffic-choked areas is well above recognized danger limits, and environmentalists say it is slowly killing street vendors, traffic policemen and drivers of the Thai capital's distinctive tuk-tuk open cabs.
Visitors often complain of sore throats, skin rashes, bad sinuses and perpetual tiredness -- all caused by absorbing large quantities of dust and toxic gases that hang in thick white fogs over the whole of central Bangkok.
Last year 1 million of Bangkok's 6.9 million people suffered from respiratory diseases.
"Everyone is dying slowly in Bangkok. That is why people are always so exhausted. You see a lot of people sleeping on the public buses. It's all because of the gas and smoke that they breathe in," said Bhicit Rattukul, a member of parliament.
Studies by the United Nations Economic and Social Commission for Asia and the Pacific show that air pollution causes and exacerbates emphysema and chronic bronchitis and that dirty air severely aggravates asthma.
Death rates from cardiovascular disease increase with air pollution because labored breathing strains the heart. Studies in China have also shown that air pollution along with smoking greatly increases the risk of lung cancer.
The high-rise buildings constructed since Thailand's economic boom took off in 1987 are trapping toxic gases that used to be blown away.
"Four years ago we did a study on air pollution and found that it was not a problem because Bangkok is built on flat land and strong air currents from the sea tended to keep the air clean," Dhira Phantumvanit of the private Thailand Development Research Institute said.
But rapid industrialization in the past few years has made the problem acute, as nearly 75 percent of Thailand's manufacturing is concentrated in the Bangkok area.
The government has done little to restrict new cars on Bangkok's clogged roads. Last year 1.6 million new cars were registered, and rising middle-class incomes will keep sending this figure up.
Levels of carbon monoxide gas are well above the safe limit in Bangkok's dense traffic areas, such as Pratunam, Rama IV, Yaowarat (Chinatown) and Charoen Krung, said Bhicit, who formed a team to study the problem last year.
Bhicit has criticized the government for doing nothing and urges motorists and street vendors to protect themselves by wearing gas masks.
"If we don't do something about (air pollution) soon, it will be like the traffic, totally unsolvable," said Dhira, director of the institute's Natural Resources and Environment Program.
"We could have done something about the traffic if we had started 10 years ago. Instead we adopted a piecemeal approach," he said.
The amount of sulfur dioxide in the air will quadruple in the next four years, and nitrogen monoxide levels will increase three times, according to institute studies.
"There has not been a serious enough effort to tackle the problem. This is typical of Third World cities, but in Bangkok we are no longer poor, so it is time to give air pollution a higher priority," Dhira said.
The only thing the government has done is promise to cut the lead content in gasoline from 0.4 percent to 0.15 in the next three years, he said.
Environmentalists say the key is cleaner technology, but they admit its introduction will be slow. The technology, which aims to prevent pollution instead of merely collecting it, is expensive.
Utilities and industries have invested heavily in their present equipment and have to show some profit before upgrading, according to U.N. surveys presented at an environmental conference in Bangkok last month.
Dhira, for his part, dismissed for the moment the idea of gas masks. "They would be too sticky in the humid weather," he said.