Two minute read. Written by a 7th grader.

We hear about air pollution all the time, but do you know what it actually is?

Air pollution is a mixture of invisible gases and solid particles or liquid droplets that float in the air. These particles and droplets are very bad for our health – their combination is known as particulate matter (PM).

Where does PM come from?

So basically, particulate matter is the sum of all solid and liquid particles that are in the air – many of which are extremely bad for our health. This complex mixture has particles such as – dust, pollen, soot, smoke, and liquid droplets. Some particles 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.

Particle pollution includes:

• PM10 : These are inhalable particles, with diameters that are generally 10 micrometers and smaller.
• PM2.5 : These are very, very fine inhalable particles. Their diameters that are generally 2.5 micrometers (or smaller). To give you an idea of how small that is – one strand of your hair is about 30 times larger than this! Yes, the average human hair is about 70 micrometers in diameter.

How does PM2.5 affect our health?

Particles of this size are so small that they can travel deep into the respiratory tract, reaching the lungs and may even get into your bloodstream. This can cause a wide range of health problems – from eye, nose, throat and lung irritation, coughing, sneezing, runny nose and shortness of breath to asthma and heart disease.

Where does PM2.5 come from?

They come from both indoors and outdoors sources. Outside, fine particles mainly come from vehicles, construction activity (sand, cement etc), firecrackers, paddy burning (when farmers burn crops to clear their fields), waste burning, burning of fuels such as wood or coal. Fine particles also form from the reaction of gases or droplets in the atmosphere from sources such as power plants.

Indoors, PM2.5 can be produced by things like tobacco smoke, cooking, burning candles or incense sticks, air fresheners, oil lamps etc.

What is AQI

AQI stands for Air quality index. It is a numerical scale used for reporting day to day air quality. The daily results of the index are used to convey to the public an estimate of air pollution level. An increase in air quality index means increased air pollution and severe threats to human health.
AQI calculations take into account air pollutants like particulate matter, ground-level ozone, sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO). Particulate matter and ozone pollutants are the worst for our human health.