January 7, 2011 — One Question per Day on Environmental Protection Areas

The main sources of dust pollution include coal dust, construction dust, and sandstorm dust

Car exhaust, dust raised by cars, and some external dust.

The main sources are: 1 construction sites and vehicles in urban areas, 2 vehicle exhaust, 3 dust, 4 unused land

Generated from urban construction activities, urban waste and its disposal processes, the operation of urban motor vehicles, road cleaning operations, as well as dust from exposed urban surfaces

All loose materials on the surface of the ground represent potential direct sources of dust. These materials are diverse and complex; for example, dust accumulated on roads, hard surfaces, roofs, etc.; loose particles on exposed soil, mountains, dried-up river valleys, farmland, etc.; as well as various uncovered piles of raw materials and waste – all of these constitute potential direct sources of dust.

Reply 1# stony_wanghc: The causes of dust generation are large areas of exposed ground, which serve as significant sources of dust in cities.

The main sources of urban dust pollution: 1. Natural dust caused by unfavorable climate conditions. The natural sources of dust include exposed soil surfaces, as well as various aerosol particles that settle on the ground. Under unfavorable climate conditions, these particulates rise from the ground into the air. Most cities in our country, especially those in the north, have a dry climate with little rainfall, and strong winds occur during winter and spring, which easily leads to dust pollution. Dust storms in northern China not only severely affect most cities in the north but can also reach some cities in the south. For example, the sandstorms this spring not only caused the air quality in northern cities such as Beijing and Hohhot to reach a severely polluted level of V, but they also had a significant impact on cities in the south such as Nanjing and Shanghai, raising the TSP pollution levels in these cities by 3 to 6 times compared to normal levels. This shows just how much of an impact sandstorms have on TSP levels in China’s environment. 2. Construction dust resulting from extensive construction activities. In recent years, China, especially in its central and western regions, has been in a period of rapid development in urban infrastructure construction. The amount of construction dust generated by construction work, demolitions, road construction, as well as the dumping and spillage of materials during transportation is increasing steadily, and this has become one of the main causes of TSP pollution. During the construction process, due to inadequate management measures, some construction sites adopted extensive construction practices. The material piles are not covered sufficiently or tightly, allowing dust-prone materials and debris to escape ； Construction waste, debris, and similar materials cannot be cleared and covered in a timely manner ； Issues such as the failure to clean the roads at construction sites in a timely manner, and the lack of proper washing for vehicles entering and leaving the site, can all lead to construction dust. 3. Dust from piled materials carried by the wind: Sites where various industrial steel slags, fly ash, and alkali slags are stored, garbage dumps, and coal storage areas are other important sources of dust. In our cities, various material storage areas can be seen everywhere, and most of them lack effective dust control measures. Each boiler (especially during the heating season) is associated with at least one coal storage site and an ash storage area; if all the material storage sites in a city are combined, some cities can cover an area of several square kilometers. With such a large scale of open-source use, if no reasonable and effective dust prevention measures are in place, it can contribute significantly to dust pollution in the atmosphere under unfavorable weather conditions. 4. Road dust that has a significant impact on pedestrians: Various solids such as debris, coal ash, lime soil, coal gangue, sand, and garbage that are scattered on roads during transportation, along with particulate matter emitted from other sources and deposited on the roads, become particles of smaller size after being crushed by passing vehicles; these particles then enter the air, forming road traffic dust. On roads with a low grade and poor landscaping on both sides, large amounts of dust often accumulate, and cars driving on such roads cause dust to fly into the air. This portion of particulate matter tends to be repeatedly lifted into the air and then settle back down, causing repeated pollution. Given that roads cover a large area, accounting for over 10% of the city’s total area, the contribution of road dust to TSP cannot be ignored. 5. Large amounts of dust on exposed surfaces: Cities in China, especially those in the north, have a low level of greenery, resulting in fragile ecological environments. There is a large amount of exposed ground along roads, in old residential areas, and in urban-rural fringe areas. Taking exposed tree pits as an example, there is basically a patch of bare land around the roots of each tree in the city. If each tree pit is considered to be 1 square meter, then with over 20 million trees in Beijing, this alone results in 20 km2 of bare land. It is evident that there is still a considerable amount of exposed ground in China’s cities, and these exposed areas serve as important sources of urban dust.

Main sources of urban dust: 1. Dust from local and surrounding areas, as well as sandstorms transported over long distances； 2. Mud clods and dust carried by motor vehicles, as well as material that spills out from the vehicles ； 3. Self-wear and consumption caused by the operation of motor vehicles (such as wear and tear of tires and brake pads, aging and degradation of exhaust purification systems, etc.) as well as exhaust emissions ； 4. Particles formed by crushing after road surface aging and damage ； 5. Particulates formed by spreading sand and saltwater in winter icy weather ； 6. Biological debris, such as dead branches and leaves, as well as fragments left over from mowing lawns or pruning trees, which are turned into particles through drying and crushing ； 7. Disposal of waste and spills, such as cigarette butts, paper scraps, and other trash ； 8. Atmospheric dust deposition ； 9. Dust generated during construction and the transportation of building materials.

The main sources of urban dust include construction work, house demolitions, road construction, exposed soil surfaces, waste material piles, and the movement of motor vehicles, among others

Urban waste and dust generated during waste removal processes； Input of natural mineral dust from outside the city ； Urban construction ； Emissions from industrial production processes ； Dust exposed on the ground......