As smog continues blanket capital Beijing and several cities in China, engineers pressed in pollution-fighting artillery called “mist canon” which sprays moist water to dilute the haze. Heavy smog that has been covering many cities in northern China has caused some authorities to bring out pollution fighting mist cannon a large machine mounted on a truck that sprays water mist, state run China Daily reported on Monday.
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The machines were initially used at construction sites and mines to reduce dust. But engineers have improved the machines to make them release tinier droplets of mist for combating fine airborne particles, Xu Yuexin, an engineer with Beijing Capital Group Boom-sound Environment Science & Technology Co Ltd, which provides the mist cannon service in parts of the capital.
“The truck works by nebulising water into tiny particles, with diameters in microns, the same as PM 2.5 and PM 10, and spraying them into the air, and then they could combine with the dust and fine particles to fall to the ground,” Xu was quoted as saying by the report.
Every winter Chinese cities are blanketed by thick smog for days together disrupting the normal life. Experts have found the mist canons are effective, but have their limits. They are the only one of the measures being taken, the report said. Bogged down with recurring smog, China experiments with number of options to fight pollution. In October this year, China deployed world’s largest outdoor air purifier designed by a Dutch engineer in Beijing.
The smog, which also covered vast areas of the country’s north, was mainly a product of windless weather that was unable to disperse pollutants, according to environmental authorities in the affected areas. The capital issued its second-highest warning against air pollution, an orange alert, on Thursday, one day before smog covered the city.
Under an orange alert, the capital takes comprehensive measures to control the emissions from companies, vehicles and construction sites. Implementation of restrictions under the alerts has been strengthened, officials said.
The mist cannon trucks are being used to spray in the mornings, and do so more frequently, some three to five times, during smoggy days. Authorities also spray special chemicals on the roads through regular watering vehicles once a week. The spray absorbs and consolidates the dust and pollutants from vehicle exhaust. The combination of the mist cannon and the chemicals “have been determined effective in reducing the fine particles”, Xu said.
The trucks started operating in October and plans call for them to continue to April, 2017. Li Gang, from the company’s marketing department, said that additional districts in Beijing and other cities may adopt the services if the mist and chemicals perform well.
Many cities in northern China, including Xi’an in Shaanxi province and Zhangjiakou in Hebei province, have used mist cannons since 2014.