Update: 2019-11-19 16:15 Source: LUFTMY
Dust or particulate matter can be from natural sources or from human activities. If the dust particles come directly from the combustion process, they are called primary dust Secondary fine dust is produced by complex chemical reactions of gaseous substances in the atmosphere. Notable sources of human dust are: motor vehicles, waste incineration plants, furnaces and heating systems, bulk material handling, animal husbandry and some industrial processes. In urban areas, road traffic is an important source of particulate matter. Another important source is the secondary dust pollution caused by the gaseous precursors from agriculture and animal husbandry.
Since 2000, the national monitoring network has been measuring PM10 and PM2.5 particles in a regional scale since 2008.The density of measurement network in metropolitan area is very high.Compared with the surrounding areas, high number of emitters and high density lead to the increase of fine dust concentration in the city. Particularly high concentrations of fine dust were recorded at traffic oriented stations, in part due to traffic related emissions such as soot, tire wear and flying dust.
According to the data provided, about 120 people per 100000 residents die each year as a result of air pollution.By contrast, the World Health Organization estimates that 7.2 million people die each year from smoking, including passive smoking, around the world.The researchers point out that their inference is related to statistical uncertainty.Therefore, the actual impact of air pollution may be higher or lower than the calculated value.For them, however, it is clear that poor air quality is one of the most important health risks (as well as high diabetes, obesity and smoking) affecting the world today.
PM10 and PM2.5 have become the front of air pollution control policy in the mid-1990s due to the new discovery of the impact on human health. Since then, some groundbreaking decisions and laws have been made at the national level. For example, EU directive 2008 / 50 / EC confirms the PM10 limit, which has been in effect since 2005, and sets a new air quality standard for PM2.5.
Can such laws and regulations produce the expected effect? Yes and no. In the last decade of the 20th century, dust and fine dust emissions decreased significantly, but since then, both in PM10 and PM2.5, the rate of reduction has slowed down. It is expected that the dust concentration in the air will continue to decline slowly in the next few years. Therefore, further measures are needed to continue to reduce particulate pollution.
In many cities, there is already an extensive and wise dust sensor network in most cases.However, in long-term measurement stations, there are usually significant differences in the quality of some sensors.Unsurprisingly, many Asian countries have developed revolutionary sensors to measure air quality in urban areas, in part for their own sake.At present, the particle load of 25 mg / m3 air is a reasonable average guide value, and the average particle load of many cities in Asia is more than four times of the average level.Therefore, it is not surprising that particulate matter sensors have become one of the best-selling electrical products for private customers in China.
However, for commercial building automation system, up to now, there is no such sensor.In view of the poor air quality in major cities in China, Siemens has developed sensors that can be integrated into home automation systems.The sensor, which is the size of a pack of cigarettes, has recently been put on the market.The new sensor can be installed on the wall, and the fine dust level in the surrounding air can be checked regularly through a small fan.The concentration of PM2.5 is precisely measured by a laser diode, which can sense the light scattering on small dust particles.The sensor is calibrated to measure important PM2.5 values, but the concentration of PM10 fines can also be estimated.
To bring relatively healthy air for the future smart city, the most realistic choice is to use sophisticated sensors and in-depth understanding of the problems we are dealing with.Environmental meteorology is a part of the extensive knowledge base of modern urban air pollution.It refers to the basic and application-oriented investigation of atmospheric environmental phenomena and processes caused by human intervention.Human impact refers to the direct or indirect environmental changes caused by human beings, including the emission and diffusion of pollutants in the air.In Asian countries, so-called haze plays an important role.The diffusion is strongly dependent on the meteorological process and the natural process on the earth.