Coal emissions from India and China are polluting the air in Bangladesh while land-clearing forest fires in Indonesia routinely send a choking haze across Singapore and Malaysia.
These factors, experts say, have turned Asia into the world's most polluted region.
Michal Krzyzanowski, a regional adviser on air quality and health for the World Health Organisation, said "transboundary air pollution is a big problem especially in densely-populated areas in East Asia".
"At the moment, there is no mechanism to regulate this transboundary problem. You need to agree on emission ceilings and common efforts to reduce the pollution."
He said it took more than 10 years for Europe to come together to work out a similar regional mechanism.
"At the moment, there is no mechanism to regulate this transboundary problem"
Michal Krzyzanowski, World Health Organisation
While many governments have toughened vehicle emission standards and phased out leaded petrol, a few big cities were doing little to enforce laws or establish effective public transportation systems.
Lew Fulton, a transport expert with the UN Environmental Programme, said the rapid growth of car and motorcycle sales constituted a big part of the air pollution problem and contributed to rising costs.
"We're not only seeing increases in pollutant emission. We're seeing huge increases in fuel consumption which is coupled tightly with [carbon dioxide] emissions."
Increased pollution also has economic and health implications in the region.
More than 500,000 people die prematurely every year due to cardiopulmonary and respiratory illnesses, according to World Health Organisation estimates.
China estimates the problem could be slowing its growth while Hong Kong fears its foul air is scaring off investors.
Cornie Huizenga, head of the Clean Air Initiative for Asian Cities, said vehicle fleets double every five years for cities in Asia.
Asia's rapid transport sector growth to contribute 60 per cent of greenhouse gases in the next few decades
Indian car sector has grown by 20 per cent annually since 2000
China poised to be world's largest car maker by 2015
Hanoi has 1.5 million motorcycles from almost none 10 years ago
Indonesia's 33 million motorcycles dwarf the country's 7.4 million car ownership
Recognising that there is no sign of vehicle sales slowing down, the delegates called on governments to boost fuel efficiency standards and promote the purchase of more fuel-efficient cars.
They also urged increased spending on clean-burning public transport projects and roads designed with bicycles and pedestrian lanes.
The conference, among the biggest in Asia, was attended by 900 experts and government officials from 20 countries.
The regional meeting comes at a time when Asia is coming to terms with the downside of the double-digit economic growth, especially in India and China.