Sales of machines boom despite doubts
Dozens of local governments in China have turned to mist cannon, or the "magic smog cleaner" as it is popularly known, to fight against heavy smog and dust, while a report released Wednesday noted that the facility's effectiveness in removing inhalable particles such as PM2.5 remains uncertain.
A total of 61 successful bids of mist cannon trucks, or multi-purpose anti-dust trucks, have been published since 2013 on ccgp.gov.cn, the China Government Procurement Net website.
The buyers are local environmental protection bureaus and utility firms in eight provinces and municipalities, including North China's Hebei Province, Central China's Henan Province, East China's Shandong Province, and Chongqing Municipality.
The average cost of a mist truck was 660,000 yuan ($95,895) while the most expensive one cost 1.33 million yuan, which was bought by the government of Jize county, Hebei Province in December 2015, the Nandu Daily reported.
Mist cannons were first used by coal mining, cement and other industries that generate huge amounts of dust. The truck sprays water into the air and dust falls to the ground after it combines with the liquid.
But there is no consensus on whether and how effectively the truck could help reduce PM2.5 - airborne particles measuring less than 2.5 micron - and ease air pollution, said the Nandu Daily.
One mist cannon truck successfully reduced the PM2.5 density from 800 micrograms per cubic meter of air to 200 within 90 minutes at a construction site in Beijing, said a manager surnamed Liu from AUTO Environment Protection Company in Kunming, Southwest China's Yunnan Province, citing an earlier experiment.
Liu added that the results vary by city.
The truck's role is limited as air moves very fast and other polluted air will soon replace the clean one, said Zhang Yuanxun, an expert on environmental sciences at the Chinese Academy of Sciences, noting that it is impossible for the trucks to eliminate heavy smog that usually engulfs a large area.
Certain particles might even react with water and expand, which may worsen the PM2.5 density, Zhang added.
Nonetheless, the sales of mist cannon trucks have witnessed an obvious increase. Lured by profits, many unqualified truck producers, some even without production permit, have rushed into the industry in recent years, while the lack of industrial standards has led to rampant counterfeiting, said Liu, adding that some producers even bribed local governments to win a bid.
In 2012, the number of manufacturers was less than 10 in China, the Nandu Daily reported. Another problem with the soaring sales is that the trucks are underutilized, leading to waste of resources, the report added.
