Forget the smoky petrol mower. However, look to the grass itself which emits volatile organic compounds including methanol, ethanol, propanone and butanone, according to Australian researchers at the Commonwealth Scientific and Industrial Research Organisation and the Monash University.
They measured grass emissions over two years, assessing how they changed as temperature, light and water supply varied. Cut grass releases 100 times more organic pollutants than untouched grass, they discovered.
These hydrocarbons "can add significantly to photochemical smog," according to Mr Ian Galbally of CSIRO. They often helped produce the "blue haze" seen over mountains, he added.