What is Fine Dust?
To understand what fine dust is, we have to understand what PM means.
PM stands for particulate matter (also called particle pollution); the term for a mixture of solid particles and liquid droplets found in the air. Some particles, such as dust, dirt, soot, or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope.
According to the size of the particles, dust is divided into total dust and fine dust. Total dust is less than 50㎛ and the fine dust is divided into PM2.5 and PM10.
PM2.5 is a inhalable particle, with diameter that are generally 2.5 micrometers and smaller. And PM10 is also a inhalable particles, with diameter that are generally 10 micrometers and smaller.
What Causes PM?
The components that make up the fine dust may vary depending on the region, season, and weather conditions. The sources of fine dust are divided into natural and artificial. Natural sources include soil dust, salt from seawater, and pollen from plants. Artificial sources are soot generated when fossil fuels such as coal and petroleum are burned in boilers or power plants, etc.
There are automobile exhaust gas, flying dust generated from construction sites, raw materials in powder form in factories, powder components in subsidiary material handling processes, and smoke from incineration plants.
Fine dust can be divided into a case that comes out from the source as fine dust in a solid state and a case where a substance released in a gaseous state causes a chemical reaction with other substances in the air to become fine dust.
Fine dust is generated through a chemical reaction in which sulfur oxides emitted from the process of burning fossil fuels such as coal and petroleum are combined with water vapor and ammonia in the atmosphere, or nitrogen oxides from automobile exhaust gas are combined with water vapor, ozone, and ammonia in the atmosphere. It is also generated, but this is a secondary occurrence.
In addition, it can be predicted that many of the fine dust in Korea came from China, but there is no clear evidence, so research is being conducted on this.