What is PM2.5 and how can you reduce your exposure from it?

You may have heard about PM2.5 and how it has become a health hazard in many countries. It is important to take precautions not only for those who work outdoors at construction sites, but also for those who commute to work or go out for a short period of time. In this article, we will introduce PM2.5 in detail, including countermeasures.

What is PM2.5?

‘PM’ is an abbreviation for ’Particulate Matter 2.5’. It refers to a type of pollutant material with a particle diameter of 2.5μm (micrometer). One micrometer is one thousandth of a millimeter, so 2.5 micrometers is only 0.0025mm. It is 1/50th the size of a hair, and 1/15th the size of cedar pollen.

The main components of PM2.5 are sulfates, nitrates, organic compounds such as carbon, and metals. In short, it refers to the ‘soot’ contained in smoke emitted from factory boilers and gas emitted by automobiles and ships. So is cigarette smoke. VOCs or volatile organic compounds contained in paint, printing ink, adhesives, etc. also cause chemical reactions in the atmosphere and generate PM2.5.

PM2.5 is harmful to health when inhaled. Because they are very small particles, when they enter the body during breathing, they reach deep into the lungs, increasing the risk of asthma and bronchitis. It has also been pointed out that PM2.5 can cause cardiovascular diseases such as heart and blood vessel diseases, and long-term inhalation can also increase the risk of lung cancer.

How to prevent PM2.5

The easiest and most effective way is to wear a mask; PM2.5 enters the body through the nose and mouth, so a mask is essential to avoid inhalation. The concentration of PM2.5 can be checked on the Internet.

Other effective measures include using an air purifier when indoors and vacuuming frequently. For vacuum cleaners, a paper bag type is suitable so that particles are not scattered when disposing of garbage. Also, when PM2.5 concentrations are high, avoid hanging laundry outside to dry or ventilating the room. When going outside, choose a type of jacket with a smooth surface to prevent PM2.5 from sticking to it. When going indoors, gently shake your body to remove adhering particles. However, since they are more likely to become airborne than pollen, it is better to drop it off gently.

How to choose a mask to prevent PM2.5

Although masks are essential to protect against PM2.5, not just any mask will do. One needs to be careful when choosing a mask. 

Standards for masks are set according to their particle collection efficiency. It is meaningless unless you wear a mask that does not allow PM2.5 ultrafine particles to pass through. Specifically, we recommend the following three types of masks with the following standards.

DS1 ( 0.06-0.10μm)

This is a mask with a particle collection efficiency of 80% or higher. It is generally referred to as a ‘dust-proof mask’.  These masks are generally called ’dust masks’.

DS2 ( 0.06 to 0.10μm)

These masks have a high particle collection efficiency of 95% or higher. These masks were also worn during the nuclear power plant accident when people were indoors.

N95 ( 0.075±0.02μm)

This is a standard set by the U.S. National Institute for Occupational Safety and Health. With a particle collection efficiency of 95% or higher, it is recognized to be as effective as DS2.

Also, if there is a gap when wearing a mask, PM2.5 will enter through it. Choose a mask of a size that fits snugly without gaps. Look for one that fits closely to the skin, especially in the nasal column, cheeks, and chin area.


The effects of PM2.5, which has been attracting attention in recent years, are by no means new to the world. To protect the health of yourself and your employees, make sure to take precautions by wearing a mask that has high particle collection efficiency.