A plumber has been airlifted to hospital after suffering serious burns in a gas explosion at Northam Recreation Centre on Tuesday.

A WorkSafe spokeswoman said the incident happened around 11am in an area where a new swimming pool is being installed.

Northam Recreation Centre. Credit:Michael Genovese

A 31-year-old man has been flown by the RAC Rescue helicopter to Fiona Stanley Hospital's burns unit.

A St John Ambulance spokeswoman said he suffered serious burns to his upper body.