Propane (C3H8C_3H_8C3H8) is widely used as a fuel in portable camping stoves.
Figure 1 shows a diagram of a portable camping stove burner.

The stove has an adjustable air collar that can be rotated to open or close the air intake holes, controlling the flow of air into the mixing tube.
Explain the effect of opening and closing the air intake holes on the products of combustion of propane, and explain the environmental and safety risks associated with burning large quantities of propane as a fuel.
Practise Edexcel GCSE Chemistry Fuels with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.