Can cigarette butts start bushfires?

It's enough to make your blood boil - the sight of someone throwing a cigarette butt out of a car window. Every year the Fire and Rescue NSW (FRNSW) is called to hundreds of roadside fires believed to be caused by discarded butts.

FRNSW Station Officer Paul Scott, based at Parramatta Fire Station, has fought many fires on busy roads and even railway tracks where the most likely cause was a dropped cigarette butt. This led him and the Community Risk Management team to develop a proposal for an awareness campaign for smokers along the lines of the high profile NSW Government anti-littering initiative, “Don’t be a tosser”. It was a good idea in theory but the connection between cigarette butts and roadside fires was still only supported by circumstantial evidence.

That was until a recent study by Jennifer Dainer, a student at the University of Technology Sydney (UTS), with help from the FRNSW and CSIRO, provided solid proof. The study, which Ms Dainer undertook as her honours project for her degree in Forensic Science, was co-supervised by Dr Anne Lear from FRNSW Corporate Risk Management and Phil Maynard from UTS.

The study

As part of the study, called Can cigarettes butts start (Bush)fires, Ms Dainer conducted outdoor trials, supervised by Station Officer Scott and three firefighters with a fire engine from Parramatta Fire Station. She lit cigarettes and threw them into grass on the side of a road in the Sydney suburb of Prospect where there was no danger to surrounding property. At the time the prevailing conditions were recorded as wind speed of 40km/h, fuel (grass) moisture content approximately 12% of oven dry weight and humidity 14%.

“On the day it was around 27°C with a north westerly wind, and it was pretty dry,” Station Officer Scott said. In three out of the 75 trials, or 4%, the grass caught alight and started to burn, requiring the firefighters to extinguish the flames.

“The fires would have progressed quite quickly if we hadn’t been there,” says Station Officer Scott. “It’s no wonder we’re called to so many fires on busy roads and freeways and by railway lines when they can start so easily.”

As well as the outdoor trials, the study also involved:

  • laboratory trials to show whether cigarette butts could ignite grassy fuel (hay) in a well-controlled environment and to identify the parameters which affect ignition potential; and
  • a survey of the number of cigarette butts on two median strips on a three lane road in Western Sydney.

The laboratory trials found cigarette butts ignited the hay in 33% of cases. Ignitions increased when the wind speed increased, fuel moisture decreased (though wetter fuels could ignite with the application of wind) and the degree of the contact between the fuel bed and combustion area of the cigarette increased.

During the survey, 426 cigarette butts were collected in a 60 square metre area of the median strip of Abbott Road, Seven Hills, over a three-week period. The wind draught created by a line of passing traffic was also recorded and found to be sufficient to increase the potential for a cigarette butt to start a fire on the roadside even if the prevailing conditions were calm.

A campaign is born

Station Officer Scott says the study finally gives the FRNSW the scientific proof that cigarette butts can cause roadside fires, including bushfires. “This confirms our view and gives us a firm basis for our new “Don’t be a firebug” campaign,” he said. “It also shows the benefits of partnerships between government agencies and universities on studies like this.”

The “Don’t be a firebug” campaign, an adapted version of “Don’t be a tosser”, is being run by the FRNSW and the NSW Rural Fire Service (RFS) in conjunction with the Department of Environment and Conservation and the Roads and Traffic Authority. The Minister for Emergency Services, Tony Kelly, announced the campaign in January 2004. Over the next few months local firefighters will kick off local versions of “Don’t be a firebug” in suburbs and towns around NSW. They’ll attach the distinctive red stickers, which show a hand dropping a cigarette butt from a car, to their appliances and vehicles as a warning to motorists. The stickers will also be available to the public from fire stations.

Station Officer Scott says it’s important to create greater public awareness around the issue.

“As well as the environmental cost associated with littering, there is also the potential for fires from dropped cigarette butts, particularly during bushfire season,” he says. “A careless act by one person may have dire consequences for others, including the firefighters who risk their lives at fires.”