What Is Particulate Matter?

There are things floating around in the air. Most of them, you cannot even see. They are a kind of air pollution called particles or particulate matter. In fact, particulate matter may be the air pollutant that most commonly affects people’s health.

Have a Look.

Particles can come in almost any shape or size, and can be solid particles or liquid droplets. 【小题1】 These groups differ in many ways. One of the differences is size. We call the bigger particles PM 10 and we call the smaller particles PM 2.5.

BIG.

The big particles are between 2.5 and 10 micrometers (from about 25 to 100 times thinner than a human hair). These particles are called PM 10 (we say “PM ten”, which stands for Particulate Matter up to 10 micrometers in size). 【小题2】

SMALL.

The small particles are smaller than 2.5 micrometers (100 times thinner than a human hair). 【小题3】 We say “PM two point five”, as in Particulate Matter up to 2.5 micrometers in size.

The smaller particles are lighter and they stay in the air longer and travel farther. PM 10 (big) particles can stay in the air for minutes or hours while PM 2.5 (small) particles can stay in the air for days or weeks. And travel? 【小题4】 PM 2.5 particles go even farther— many hundreds of miles.

Particulate Matter and Your Health.

Both PM 10 (big) and PM 2.5 (small) particles can cause health problems, specifically respiratory (呼吸的) health. When you breathe, you take in the air along with any particles that are in the air, like heavy metals and cancer-causing organic compounds. 【小题5】 Exposure to particulate matter leads to increased use of medication and more visits to the doctor or the emergency room.