The system tracks six major pollutants, including PM2.5 (fine particulate matter with diameters of 2.5 microns or less), enabling standardized public data reporting. Air quality is considered good when the PM2.5 concentration is below 100 micrograms per cubic meter on a scale of 0 (excellent) to 500 (hazardous). Back in 2013, Beijing recorded just 176 days of good air. Since then, that number has steadily increased year by year.

A Beijing resident surnamed Xiong still remembers the smoggy days in 2013. "Back then, Beijing, especially in winter, was often shrouded in a haze. The air carried a constant smell of coal burning, which really affected your mood," he told Beijing Review. "We had to wear masks outdoors and bought air purifiers for our homes. Back then, seeing blue skies and white clouds was exciting. But in recent years, the air quality seems to have improved dramatically. Blue skies have become the norm, and our air purifiers have sat unused for a long time."

A more striking visual comparison of Beijing's air quality progress over the past decade was unveiled during the Third Session of the 14th National People's Congress, the country's top legislature, held in Beijing this March. Minister of Ecology and Environment Huang Runqiu on March 8 displayed two filter membranes collected from Beijing's air quality monitoring instruments. The 2015 membrane appeared dark gray, while the 2024 one was light gray. This contrast offers the most direct illustration of Beijing's air quality improvement. 

Coal to clean 

Behind this seemingly "sudden" transformation lies years of systematic effort, with initiatives like coal-to-electricity conversion (replacing coal-burning with electric heating) playing a major role.

At the 29th World Gas Conference in Beijing on May 23, Yang Xiuling, Director of the Beijing Municipal Commission of Development and Reform, highlighted a dramatic shift: Beijing's coal consumption plummeted from 21.8 million tons in 2012 to under 600,000 tons in 2024, now accounting for less than 1 percent of the city's total energy consumption.

What does this mean? Wang Zifa, a researcher at the Institute of Atmospheric Physics of the Chinese Academy of Sciences, explained to Xinhua News Agency that as one of north China's largest heating-area cities, Beijing had long relied on coal as its primary heating fuel. The city's first PM2.5 source analysis in 2014 confirmed coal combustion as a major local pollution contributor.

However, efforts to tackle the issue got underway much earlier. Starting in the early 2000s, Beijing launched its coal-to-electricity program for clean heating. Xicheng District pioneered this effort, specifically targeting residents in low-rise neighborhoods within conservation areas that lacked access to centralized heating.

Beijing's centralized heating system is a government-managed district heating network that provides indoor heating to residential and commercial buildings during winter (typically November 15 to March 15).

These neighborhoods had long depended on small coal stoves, causing severe ground-level pollution. Similarly, older residential buildings (mostly constructed in the 1950s-60s) without heating systems also contributed considerably, with many households still using coal briquettes for warmth.

Wang Yu, a senior engineer at the Ecology and Environment Bureau of Xicheng District, said from 2003 to 2015, the district implemented 10 large-scale coal-to-electricity initiatives targeting low-rise and old residential buildings. These efforts transitioned nearly 160,000 households to electric heating. By late 2015, Xicheng had become Beijing's first coal-free zone, fully eliminating coal combustion pollution.

Beyond heating reforms, Beijing established strict emission standards for other stationary sources like gas turbines and boilers, progressively tightening limits. This systematic approach has driven coal use down 97 percent since 2012, while annual PM2.5 concentration fell from 89.5 mg per cubic meter in 2013 to 30.5 in 2024, a 65.9-percent reduction.

In just one decade, Beijing achieved what took developed nations 20–30 years—a feat dubbed the "Beijing Miracle" by the United Nations Environment Programme.

Challenges and goals 

The dramatic drop in PM2.5 concentration is a remarkable progress. Yet can Beijing afford to "take a breather" in its air pollution battle?

Nie Lei, Vice President of the Beijing Municipal Research Institute of Environmental Protection, offered a vivid analogy: Beijing's air governance now resembles a 100-kg person losing weight. Shedding the first 10 kg proves relatively straightforward, but each subsequent kg demands exponentially greater effort.

"Any relaxation risks rebound. Even after hitting targets, maintenance is non-negotiable, and sustaining gains requires fundamentally transforming habits," he told newspaper Beijing Daily.

This challenge is obvious. China's 2027 target, set by the State Council, the highest state administrative organ, in January 2024, is a national PM2.5 average below 28 mg per cubic meter. Despite achieving full compliance since 2021, Beijing's readings—30 (2022), 32 (2023) and 30.5 (2024) mg per cubic meter—remain short of the goal.

How can Beijing meet the new target? Nie stressed two priorities: deeper local emission cuts and sustained collective action across the Beijing-Tianjin-Hebei region.

Nie highlighted that mobile emissions currently dominate local pollution sources. With over 6.4 million vehicles, especially high-emission ones like heavy-duty diesel trucks, Beijing has great potential for transitioning to new-energy vehicles.

New-energy vehicles are automobiles fully or predominantly powered by electric energy, including plug-in vehicles, battery electric vehicles, plug-in hybrid electric vehicles and fuel-cell electric vehicles.

"Stricter vehicle standards drive industry-wide technological upgrades," he said, adding that "high standards, advanced tech and superior performance are foundational to high-quality development."

Domestic sources rank second among Beijing's local pollution sources, spanning the diverse sectors as Nie specified: essential urban services (auto repair spray-painting, restaurant emissions), construction materials (paints, adhesives) and household activities. These sources demand precision governance. 

Nie stressed that sustained progress requires coordinated regional action. "Breakthroughs demand collaboration across Beijing-Tianjin-Hebei and neighboring areas," he said. Since 2015, environmental authorities have operated a joint enforcement mechanism and provided critical institutional support. "Harnessing cutting-edge technologies for precision pollution control needs innovative regional solutions," he added.

Beijing's experience also contributes to global air governance cooperation. Earlier this year, the city signed a three-year memorandum of understanding with Bangkok, Thailand, focusing on collaborative air quality monitoring and management. Over the next three years, the two cities will prioritize practical cooperation in addressing atmospheric pollution.

Xie Jinkai, head of the Atmospheric Environment Department at the Beijing Municipal Ecology and Environment Bureau, told Xinhua News Agency that "Beijing Blue" has become a hallmark achievement in China's air pollution control efforts.

However, she emphasized that the current progress in air quality remains fragile. Adverse weather conditions, such as temperature inversions and stagnant air during autumn and winter, can quickly lead to pollutant accumulation, chemical transformation and widespread regional pollution episodes. "Improving air quality is a long-term, complex and challenging mission," she said.

Copyedited by Elsbeth van Paridon 

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