Despite promises to cut steel overcapacity, China actually brought more steel production online last year, resulting in a surge in air pollution in northern China, especially around Beijing, according to a report released this week by Greenpeace East Asia.

The growth in operating capacity was more than twice the total steel making capacity of Britain, the report said.

The increase in steel production, which is powered by the burning of coal, also means that levels of greenhouse gas emissions from that sector almost certainly grew last year, compared with 2015 levels. Greenhouse gases are the main factor behind the acceleration of climate change. The steel industry is the second biggest emitter of carbon dioxide, the main greenhouse gas; the first is power generation, which also relies mostly on coal.

China is the biggest greenhouse gas emitter in the world, ahead of the United States.

The report, released Monday, shows how powerful state-owned enterprises and local officials have acted to keep steel companies operating out of economic self-interest despite a serious overcapacity problem in the industry. And as China’s economic growth slows, local governments feel rising pressure to support factory jobs to avoid domestic unrest.

The report said 10 Chinese provinces increased their operating steel production capacity. The greatest increases were in Shanxi and Hebei, which are close to Beijing and have some of the most toxic air in the world. Only six provinces had a net decrease, the report said.

The Chinese consulting firm Custeel, under commission from Greenpeace East Asia, did the main research for the report. The firm based its calculations on surveys and official documents, including ones from local governments.

Growth in steel demand across China has been slowing since 2011, leading to pledges by officials to cut capacity.

Officials said that efforts last year to cut capacity had exceeded targets set for the year. But the research by Custeel showed that officials pulled a sleight of hand in making that declaration — many of the cuts were to plants that had already been idle. As a result, only 23 million metric tons of capacity was actually closed, the report said.

Those closures curtailed supply at the same time that government stimulus led to a short-term uptick in demand. Officials and companies restarted some plants that had previously been suspended, the report said. That production capacity was equal to 49 million metric tons, about the same as Germany’s total steel making capacity.

China also added 12 million metric tons of new capacity.

As a result, the net increase in operating steel capacity for 2016 was 36.5 million metric tons, the report said. Eighty percent of that increase came from just three provinces: Hebei, Shanxi and Tianjin.

Some government policies have gone against the stated goal of cutting overcapacity. From 2013 to 2015, bank lending and government subsidies to the steel industry increased. In 2016, stimulus policies “created a miniboom in construction, artificially inflating steel demand and steel prices.”

The report said most of the capacity that was cut came from closures of plants that were privately owned or owned by central state enterprises, which suggested that local state-owned enterprises and governments were protecting their own interests.

A Greenpeace analysis of Beijing air quality data showed that steady progress in curbing air pollution in Beijing stalled last year. In some months late in the year, air quality worsened over 2015. In the first five weeks of 2017, the concentration of PM2.5, or particulate matter of a size deemed especially harmful, was almost twice as much as the same period in 2016.

In 2013, the central government announced goals to cut coal use in three major population centers in China, including in the large region around Beijing, to try to bring down levels of air pollution, among the worst in the world.

Stimulus policies last year also led to an increase in coal prices during one period, though climate change researchers say they expect data to show that overall coal consumption in China declined in 2016 compared with 2015.