With many cities in northeast China smothered by thick smog in recent months, the widespread use of face masks and air purifiers comes as no surprise. But some local governments have turned to a less familiar tool for combating air pollution: the mist cannon.
Late last year, Hunan Jiujiu Mining Safety Equipment began marketing a specialized version of the dust control machines that have been used for years by cement, steel, and coal mining companies. Founded in 2011, the company is based in Changsha, the capital of the Hunan province, an area long known for coal mining.
The machines work by nebulizing liquid into tiny particles and spraying them into the air, where they combine with harmful dust particles to form water droplets that fall to the ground. This reduces the chance of workers (especially miners) developing lung and respiratory problems.
The same idea can help the residents of heavily polluted cities, the company reasons. Seeing a potential new market, it started developing ”multi-function dust control machines” in 2013 and, at the end of last year, began marketing them to government departments involved in infrastructure, sanitation, demolition, and the environment. A marketing video (in Chinese) by the company starts with a scene of urban pollution:
A mobile version of the machine that can be mounted on a vehicle and operated while in motion starts at about 600,000 yuan ($93,000). A stationary version starts much lower, at around 80,000 yuan. Those prices are roughly equivalent to non-specialized dust control machines on the market.
According to the company, the upgraded machine’s main advantages are that it consumes less electricity and water, and that it can produce smaller particles than its traditional brethren (down to 10 microns, compared to 30). When the size of the nebulized liquid particles equals that of the dust, the company says, the two kinds of substances are mostly likely to combine to form a water drop.
Of course, some of the most troublesome pollution particles are smaller than 10 microns. Two commonly used pollution measurements are of PM10 (particles 10 microns and below) and PM2.5 (2.5 microns and below). The company admits the new machine can’t catch everything, but says it’s still effective. Two of the machines eliminated the dust from a six-story building’s explosive demolition in about five minutes, office director Lu Huang told Quartz.
Many cities have been sold on the idea. The first government buyer of the multi-function machines was the Guangxi province’s city of Guigang, which early this year acquired five of the machines to control dust and smog. Other customers include the cities of Changsha and Zhuzhou (both in the Hunan province), and cities in the provinces of Shandong and Shanxi, as well as in Inner Mongolia.
With parts of China getting hit by staggering levels of pollution, sales have jumped in recent months, according to the company, although executives didn’t want to specify how much.
Changsha’s Yuhua district used one of the machines on Dec. 8 (see photo above). Zhong Zhihong, the district’s director of the environmental protection, told Science and Technology Daily (link in Chinese) that “the multi-function dust control machines could work without gathering water on the road and won’t affect traffic. Yuhua district will use the machine more frequently during heavily polluted days.”
May Shi is on Twitter at @aMay_Shi.