When harmful gases, dust and smoke get into the air it’s called “air pollution”. When we breathe in harmful gases and particles, they can make existing conditions like asthma worse and increase our chances of becoming unwell in the future.
It is good to remember that most of the gases in the air either help us, like oxygen, or have no effect on us. However, some things that humans do, like burning coal and driving cars, release gases and particles which are bad for us, such as Nitrogen Dioxide (NO2), Particulate Matter (PM2.5 and PM10). And it is those that we call “air pollution”.