@Paul Osborne No, you misunderstood. Any petrol engine, be it in a car, lawn mower, boat or aeroplane is not silent and emits exhaust fumes. The question is how much. Some pessimistic claims made on this forum about how much are simply wrong. It would be more sensible to compare the proposed airfield movements to the noise and pollution we might produce when we drive to the coast for a spot of fishing, take the kids to football practice, go to the cinema, etc.