Asked by: Rosalind Patterson, USA
The US Forest Service has commercial contracts for a fleet of 300 helicopters and more than 50 fixed-wing aeroplanes, which dump 40 million litres of fire-retardant sludge onto forest fires each year. But surprisingly there isn’t very good evidence that it works. A 2011 study found no correlation between the use of fire retardant and fire-fighting success rates. Once a wildfire is raging, airdrops seem to be more about public relations than effective firefighting.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
