why are you not allowed to use your phone a petrol station?

Question: why are you not allowed to use your phone a petrol station?
- Keywords:
  petrol,
  phone,
  station
Asked by Watsits to Andy, Diana, James, Mary Jane, Wil on 9 Mar 2017.
- Wilhelmiina Toivo answered on 9 Mar 2017:
  
  People think the electromagnetic radiation from a cell phone can ignite the petrol vapour and make a fire. There is very little evidence for this though, so I would say it’s extremely unlikely (but better safe than sorry!)

Question: why are you not allowed to use your phone a petrol station?