Tianjin Municipality, one of the smoggiest Chinese cities, is engaged in a painstaking battle against dust pollution, the leading contributor to the city's PM2.5 concentration.
The city's construction sites covers a total area of 212 square kilometers in 2014, almost equal to the size of Shijiazhuang, capital city of the nearby Hebei Province, officials with Tianjin Environmental Protection Bureau told Xinhua.
Tianjin, about 100 kilometers away from China's capital Beijing, is prone to clouds of construction dust. An analysis conducted by the bureau last year found about 30 percent of the city's PM2.5 (airborne particles smaller than 2.5 microns in diameter) pollution was from dust, followed by coal and motor vehicle exhaust, which accounted for 27 and 20 percent respectively.
In spring when the weather is drier and construction sites are busier, dust pollution can contribute 46 percent to the city's PM2.5 concentration, according to the bureau. He Jianqiang, deputy head of the atmosphere center under the bureau, said the total area of Tianjin's construction sites in 2014 was about two times of that in 2010, and some sites are still without adequate dust control measures.
As part of the Beijing-Tianjin-Hebei integrated development plan and a test field of China's pilot free trade zone, Tianjin has been witnessing rapid expansion in recent years.
Shi Hanghua, official with the city's construction projects quality and safety supervision department, said there are currently over 1,000 polluting construction sites in the city. Some operations, such as dregs transportation, are not up to environmental protection standards.
The sites are also scattered, posing a bigger challenge to the understaffed supervision department. Recognizing the severity of dust pollution, Tianjin's municipal legislature passed an air pollution control law in early 2015, which defines the responsibilities of various authorities. The authorities then made their own law enforcement guidelines.
At the Yahui commercial center construction site in Hexi District, six newly installed surveillance cameras and dust monitoring equipment are overseeing dust control. All trucks must have their tires cleaned before leaving the site.
Shi Hanghua said, all construction sites in the city's downtown areas have been newly installed with the equipment, the dust monitoring machines will alarm supervisors if excessive concentration of dust is detected in the air.
Additionally, all dregs transportation vehicles are required to be airtight and equipped with GPS. The drivers have to receive certain training before taking their position, he said.
"A joint law enforcement team composed of staff from different departments of the municipal government has been formed to oversee dust control, and the supervision efficiency is much higher than before." Shi added, "We are also considering using a kind of spray to solidify the mounds on the construction sites."
Experts are expecting cleaner air in Tianjin with the strengthened measures in place, while they also noted that it will be a protracted battle considering the huge size of the construction sites.
He Jianqiang said, the city is undergoing a new round of rapid development and expansion, the problem of dust will not be easily cured within a short period of time. Bao Jingling, former chief engineer of Tianjin Environmental Protection Bureau, noted that to better combat the problem of dust, multiple measures have to be adopted.
"More needs to be done to upgrade the city's infrastructure. Many roads are plagued with inadequate drainage, the dust washed down by street sprinklers cannot be effectively drained away and becomes mud, causing more dust pollution," he said.
The city also needs to restore its shrinking wetland, as it works as a natural dust catcher, he added. Last year, 30 major cities conducted an air pollutant analysis mandated by China's environmental authority.
Beijing's PM2.5 was found to be caused mainly by motor vehicle exhaust, while in Shijiazhuang, capital city of the adjacent Hebei Province, the main cause of smog was found to be coal burning.
Analyzing the exact causes of smog allows different places to take specified measures to better curb smog, said Feng Yinchang, professor with the college of environmental science and engineering of Nankai University in Tianjin.
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