Nga Trang has nearly stopped going out in the evening and forbids her kids to play outdoors after school because air pollution from burning trash gets worse in her neighbourhood in Hanoi in the late afternoon.

A Hanoian by birth, Nga, 44, is one of many residents of Vietnam's capital whose daily routine is altered by heavy air pollution, which a global report released on Tuesday said is worsening.

The annual report by IQAir, an air quality technology company, found Hanoi was one of the world's worst capital cities last year for air quality.

The World Health Organisation (WHO) in a statement said under a conservative estimate around 60,000 deaths in the 100-million-people nation are related annually to air pollution. Experts warn that pollution also impacts tourism and the whole economy.

Nga collected dozens of signatures earlier this month to stop the burning of waste at a site near her apartment in a densely populated district.

"This affects us more directly than other sources of pollution as we can smell and see it every day," she said.

Vehicle emissions, industrial activities and poor waste management practices including the burning of rubbish are among Hanoi's main sources of pollution, said WHO's representative in Vietnam, Angela Pratt, urging Vietnam to consider setting maximum acceptable levels of air pollutants.

Vietnam's health and environment ministries and Hanoi authorities did not reply to requests for comment and data about the incidence of pollution-related diseases in the city of over 8 million people.

In a 2021 report, the environment ministry said respiratory diseases accounted for 11% of deaths in Vietnam, with healthcare-related costs estimated at around $81 million annually in Hanoi alone.

The city has frequently topped IQAir's daily global list of most-polluted cities this year. Last year it recorded an average concentration of small and hazardous airborne particles, known as PM 2.5, nearly nine times higher than limits recommended by the WHO, according to IQAir.

That made it the eighth-worst capital city out of 114 monitored.

BLOW TO ECONOMY

Beyond health, the smog is also having a negative impact on tourism, which accounted for over 6% of Vietnam's gross domestic product last year, according to the environment ministry.

Travel medicine doctor Amornphat Kitro, who has studied health risks for tourists in Southeast Asia, said foreign arrivals to the northern Thai city of Chiang Mai fall in the months with most pollution, while resident expats often leave in those periods.

Giovanna Macchi, 48, an Italian national who has lived in Hanoi for seven years, said she limits her children's outdoor activities, leaves the city whenever she can and tells friends not to visit the city in the periods of worst pollution.

"We are considering to move out of Hanoi because of the air pollution," she said.