Blue skies return to Hanoi as city breathes clean air again

THE HANOI TIMES — An exceptional environmental milestone was marked in Hanoi today, with air quality readings across the city hitting the 'good' range – a rare occurrence in recent months.

At 9:30 AM, the streets shimmered in the soft morning sunlight. The usual haze had lifted and, for once, the skyline was clear. Birds could be heard above the hum of traffic.

“I didn't need to squint through the smog,” said Nguyen Hien, a retired teacher from Thanh Xuan district. “It reminded me of Hanoi 30 years ago.”

The city’s air quality monitoring system today recorded an unusual occurrence: all of the monitoring stations across the capital returned “good” results. The air quality index (AQI) at the five key sites monitored by the Center for Agricultural and Environmental Engineering ranged from 19 to 35 (the index less than 50 is ‘good’, no risk to human health). The results in other areas were as follows: Minh Khai Ward in Bac Tu Liem District showed 19, Dao Duy Tu Street in the Old Quarter at 20, Van Ha Commune in Dong Anh District 25, Luu Quang Vu Street in Cau Giay 33, and An Khanh Commune in Hoai Duc 35.

Additional data from the Northern Environmental Monitoring Center corroborated this trend. AQI readings in other populous areas, such as Nguyen Van Cu Street (Long Bien District), Hanoi University of Science and Technology (Giai Phong Street), and Thanh Xuan Park, hovered around 42 to 46. For the time being, the Hanoi sky was blue again.

To many, it was more than just data. "I took my three-year-old to the park without a mask," said Pham Hoai Anh, a mother who lives in the Giang Vo neighborhood. "It felt like we were on vacation, but we were just in our own neighborhood, finally somewhere we could breathe."

This sudden clarity marked a striking reversal. In January 2025, Hanoi topped the global pollution charts, with AQI levels surpassing 300 on multiple days. Entire districts disappeared behind walls of haze. Schools issued warnings. Masks became essential. International media outlets reported on the city as one of the most polluted in the world.

So, what explains the change?

Experts point to a combination of favorable weather and policy momentum. Light rain and strong winds in the preceding days helped disperse the accumulated fine dust, especially the PM2.5 particles. Since May 25 fell on a Saturday, there was lower traffic volume and a break in construction—two of the city's biggest sources of pollution.

Yet this wasn’t all due to chance. In April, Deputy Prime Minister Tran Hong Ha issued a directive requiring Hanoi and Ho Chi Minh City to design five-year action plans to achieve safe air quality levels. These plans require emission source inventories, measurable targets, and stricter enforcement protocols.

Since then, Hanoi has accelerated the expansion of its monitoring networks and initiated the revision of outdated vehicle and factory emission standards. Public agencies have also started collaborating more closely with private firms to pilot technology-based environmental solutions, such as real-time sensors and predictive data models.

Still, experts remain cautious. "One clean day does not mean a clean month," said a senior scientist at the National Institute of Environmental Health Sciences. "It's encouraging, but we'll need structural changes to make it last."

Still, the impact on daily life was immediate. Photos of blue skies began circulating online. Children played outdoors without coughing fits. "I delivered packages all morning and didn't feel dizzy once," said Nguyen Van Tu, a motorbike courier who works in Dong Da and Ba Dinh districts. "Normally, by noon, my throat burns. Today, it didn’t.”

Despite its progress, Hanoi still faces significant environmental challenges. The city’s rapid growth continues to strain its infrastructure. The large number of aging vehicles, coal-fired electricity plants in surrounding provinces, and operations of industrial zones all contribute to the poor air quality.

Experts have also noted inconsistent enforcement, particularly in rural areas where agricultural and waste burning persist. While the transition to electric vehicles has begun, it remains slow due to cost and charging limitations.

The Hanoi authorities are seeking help from the private sector. In a recent agreement, the city partnered with Vingroup to implement smart environmental monitoring tools and encourage sustainable urban development.

The improvement on May 25 offers a glimpse of what could be possible. It shows that clean air is possible in Hanoi with the right combination of climate, reduced emissions, and government commitment. Whether this becomes a trend or a one-day anomaly depends on what happens next.

As authorities move forward with their action plans, the challenge will be to make those rare green days the new normal for the city.