How does asthma affect your breathing? What other substances except cigarretes block your lungs?

Question: How does asthma affect your breathing? What other substances except cigarretes block your lungs?
- Keywords:
  breathing,
  lungs,
  pollution
Asked by to John on 14 Mar 2014. This question was also asked by .
- John Foster answered on 14 Mar 2014:
  
  Asthma happens when something irritates your airways and triggers them to become inflamed (swell up). The muscles around the airways tighten causing them to become very narrow. The amount of mucous, which is the sticky stuff that traps bacteria, can also increase. All this makes it difficult to breath and can cause you to cough and for your chest to feel tight.
  
  Cigarette smoke is very bad for your lungs, but other things such as pollution from cars and industrial chemicals such as asbestos (this was once used as a building material) can damage your lungs.

Question: How does asthma affect your breathing? What other substances except cigarretes block your lungs?