Decades of red-hot economic growth in China have lifted hundreds of millions out of poverty, but rapid industrialisation has taken its toll on the environment and led to dangerous levels of air pollution in the capital city.

Over the past seven years, levels of particulate matter in Beijing’s air smaller than 2.5 micrometres in diameter (PM2.5) averaged nearly five times the recommended daily level set by the World Health Organization, according to data from a monitoring station at the U.S. embassy.

The medical implications of sustained exposure are sobering. A study by Greenpeace and scientists at Peking University based on 2013 data attributed more than 257,000 premature deaths in 31 Chinese cities to PM2.5, making it a bigger killer than smoking.

Awareness of the dangers of Beijing’s skies is on the rise, and people are becoming increasingly concerned about medical implications of sustained exposure to the polluted air.

Liu Ruiqiang uses a handheld pollution sensor to measure air quality on his balcony. For years, he put up with chronic smog in Beijing, but he didn’t want to take any chances when his daughter was born.

On days when air pollution reaches hazardous levels, little Yunshu is confined to their home, where a pair of constantly whirring air purifiers make it safer to breathe.

Liu, who says he’s a lower-middle class Beijinger, estimates he has spent more than 40,000 yuan ($6,375) in the past couple of years to counter the effects of pollution.

“If we don’t think of a way to balance it out or find some basic ways to help us recover, eventually our health will be destroyed,” the 37-year-old said.

Rising public discontent over the state of the environment has proved a powerful catalyst for change amid signs the government is starting to take the environment seriously.

China will “declare war on pollution,” Premier Li Keqiang told parliament in an opening address in 2014. A tougher environmental law took effect at the start of the year.

But citizens must push harder to ensure environmental measures triumph over business interests, one expert said.

“In China, what we need is wide participation from society, and monitoring from the public to make sure the laws are implemented,” said Ma Jun, founder of the Institute of Public and Environmental Affairs.

For now, Liu sees no silver lining in Beijing’s toxic cloud.

“It’s very unlikely we’ll see the pollution issue being solved in the next 10 years,” he said. “It’s not realistic.”