Nitrogen dioxide
Nitrogen dioxide is easier to find. He can normally be found around vehicles and busy roads. He is a reddish, brown gas that smells horrible. He is also poisonous and very harmful to us. If you breathed in lots of nitrogen dioxide it would make breathing difficult, give you pains in your chest and it might damage your lungs.
Nitrogen dioxide is part of a family called the 'oxides of nitrogen'. His sister, nitric oxide is a bit nicer - she is colourless, doesn't smell and isn't harmful to humans at all. But when nitric oxide meets oxygen in the air, she very quickly changes and becomes nitrogen dioxide, which is bad for us and the environment.
So, anything that emits nitric oxide into the air we breathe can make nitrogen dioxide pollution. This includes almost anything that burns fuels, but especially cars and other vehicles.
Once you've read about all the suspects that cause pollution, take the quiz by clicking below:
