A truck-mounted mist cannon blows away dust in the air on a hazy day. Photo: Tencent

China is rolling out a new arsenal of weaponry in its never-ending war on smog, after traditional tools like masks and indoor purifiers failed to chase the fumes away.

Roadside fans, water vaporizers and huge mist cannons, usually mounted on trucks to disperse dust, are among the gadgets being deployed in an effort to clean the air of fine airborne particles. The main target is dangerous particulate matter with a diameter of less than 2.5 microns (the diameter of a human hair), which is commonly known as PM2.5. It can become lodged in the lungs when inhaled.

Cannon trucks have been patrolling major streets in Beijing and a number of other cities to counter air pollution within small areas  whenever the filthy haze blankets northern China.

A mist cannon at Zhengzhou in central China. Photo: Handout

Working in tandem with legions of powerful fans, each mist cannon is able to reduce the PM2.5 density within a radius of 100 meters by a third, according to the Beijing Municipal Environmental Protection Bureau (BMEPB). It said a trial scheme using cannons and fans to blow away smog would be implemented city-wide this year.

In a separate trial in Xian, capital of northwestern China’s Shaanxi province, a 100-meter air-purification tower developed by the Chinese Academy of Sciences has been erected to help reduce smog levels. It will produce  more than 10 million cubic meters of clean air a day, the Hong Kong-based South China Morning Post newspaper reported.

Polluted air is sucked into the tower and heated up by solar energy. The hot air then rises through the tower and passes through multiple layers of cleaning filters. The design of the tower resembles a glasshouse.

The 100-meter air purification tower in Xian. Photo: Handout

However, the creative solutions have not come without some controversy. China’s environmental watchdog has named and shamed officials in two cities for using mist cannons to wash pollutants from around monitoring stations and thus “clean up” air quality readings.

Officials at Xinyu in Jiangxi province and Xinyang in Henan province  have been held for questioning, said the Ministry of Environmental Protection.

“It’s illegal to interfere with air quality monitoring, whether these vehicles were assigned to do it on purpose or not,” the ministry noted.

“Offenders can be criminally prosecuted and face tougher penalties,” said Ma Yong, an environmental law researcher for the Supreme People’s Court, told China Daily.

In addition to protecting the integrity of monitoring data so it can get a clear picture of the pollution situation, the ministry has conducted field inspections at 2,125 locations in 28 cities in northern China in an effort to identify violations, especially during periods of heavy smog.

A cloud of heavy smog clings over Beijing. Photo: Reuters

Meanwhile, Greenpeace has acknowledged the authorities’ efforts to  clean up the air in Beijing and its adjoining conurbation by restricting coal use and industrial activity.

Beijing’s pollution level dropped 54% in the fourth quarter of 2017 from a year earlier, the environmental group noted in a report. However, it warned that policies still favored coal and heavy industry, hampering further progress.

The BMEPB said the city had met its air-quality targets in 2017 after a crackdown on polluters and improved weather conditions. Average  concentrations of PM2.5 dropped by 35.6% in 2017 from 2012 to 58 micrograms per cubic meter.

The official PM2.5 standard is only 35 micrograms, while a limit of 10 micrograms is recommended by the World Health Organization.

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