Hanoi’s smog puzzle : Vehicle emissions contribute just 15%, officials say

Despite popular belief, vehicle emissions are not the main culprit behind Hanoi’s worsening air quality, making up just 15% of total pollution, according to officials, who however say cutting emissions remains urgent.

« Vehicle emissions make up about 15% of the pollution, while dust from traffic contributes 23%, » said Nguyen Hoang Anh, acting head of Environmental Quality Management at the Ministry of Agriculture and Environment. « The main source of pollution is actually the combination of vehicle activity and weather conditions. »

Speaking at a forum on electric vehicle transition earlier this month, Anh said Hanoi experienced 47 days of « very poor » air quality in the last quarter of 2024. On some days, the Air Quality Index (AQI) spiked as high as 246.

Although traffic is often blamed for up to 60% of air pollution in the capital, Anh clarified that not all of that comes from exhaust fumes.

« Industrial dust accounts for about 29%, construction activities add 17 to 18%, and open burning, such as straw or tire fires, contributes 15 to 16%. These numbers are based on data from many sources and included in the Ministry’s report to the Prime Minister, » she said.

Anh also emphasized that accurately tracking emissions is still out of reach. « We haven’t been able to conduct a full inventory because emission sources are dynamic, the budget is limited, and there’s no standard method in place, » she said.

« But based on what we’ve seen, pollution in Hanoi tends to be worse than in Ho Chi Minh City due to weather. In the past, peak hours were between 6 and 8 a.m., now they’re usually from 9 to 12. »

A 2023 World Bank report backed up that view, finding that only one-third of Hanoi’s PM2.5, the fine particulate matter that poses the biggest health risk, comes from within the city. The rest drifts in from nearby provinces and regions.

According to the report, transportation is responsible for roughly 25% of PM2.5. Industrial activity, including large factories, power plants and traditional craft villages, adds 35%. Household biomass cooking contributes 10%, livestock and fertilizer emissions account for 20%, and about 7% comes from burning agricultural waste in open fields.

At the same event, Hoang Anh Le of the University of Natural Sciences said emissions vary depending on the time of day and type of vehicle.

« During the day, motorbikes are the main source. At night, heavy trucks take over. The emissions also change with the seasons, » he said.

Motorbikes, which dominate Hanoi’s roads, are particularly problematic. « They use more fuel and emit directly through the exhaust without any filtration, making them more polluting than cars, » Le explained. « On top of that, vehicles in Hanoi move slowly, only about 35 kph on average, which increases fuel use and emissions. »

Phan Truong Thanh, head of investment finance at Hanoi’s Department of Construction, said the city is home to roughly 6.9 million motorbikes, about 95% of them gasoline-powered. Under Hanoi’s electric vehicle transition plan, nine wards in the city’s urban core will be directly affected, six of which lie entirely within Ring Road 1.

Preliminary data shows that this zone has about 600,000 residents and 450,000 registered motorbikes, not counting vehicles coming in from outside. « We’re now conducting surveys to gather baseline data, which will guide our low-emission zone policy, » Thanh said.

« At the same time, we’re investing in better infrastructure, especially public transportation. That’s the core issue. Hanoi does not encourage continued motorbike use. »

Hoang Duong Tung, chairman of the Vietnam Clean Air Network, said the shift to electric vehicles won’t be easy, but the benefits are clear.

« What people need are detailed policies. They need to see that this isn’t just a challenge, it’s an upgrade to a smarter, more convenient way of life, » he said. « That’s how the city can show it’s serious. »

On July 12, Prime Minister Pham Minh Chinh issued a directive that laid out a bold roadmap for phasing out fossil-fuel vehicles in Hanoi. By July 1, 2026, all gasoline-powered motorcycles and scooters will be banned from operating in downtown area within Ring Road 1.

Starting Jan. 1, 2028, privately owned fossil-fuel cars will also be restricted within both Ring Roads 1 and 2. By 2030, the ban will extend to all personal fossil-fueled vehicles within Ring Road 3 along the city’s outlying areas.

By Gia Chinh – VnEXpress.net – July 27, 2025