Ethanol fuel may harm lungs
Ethanol-fuelled vehicles could contribute to more illnesses and deaths from respiratory disease than petrol-powered cars and trucks, says US research.
This is because some ethanol blends can increase atmospheric ozone levels, the researchers say, a key ingredient of smog.
If all cars and trucks were replaced by vehicles fuelled by ethanol, deaths related to increased ozone would rise by about 4% in the US, according to the study in the journal Environmental Science and Technology.
"Our results show that a high blend of ethanol poses an equal or greater risk to public health than [petrol], which already causes significant health damage," says Associate Professor Mark Jacobson, an atmospheric scientist at Stanford University and lead author of the study.
The study raises questions about ethanol, a fuel produced from corn or other crops, which many hope will reduce oil dependency and air pollution.
Jacobson ran computer tests simulating atmospheric conditions in the US in 2020, when ethanol-fuelled cars are expected to be widely available.
His simulation focused on Los Angeles because of its poor air quality and dense population, he says.
He programmed the computer to run air-quality simulations comparing two scenarios: one where all cars, trucks, motorcycles and other vehicles are powered by petrol and another where the same fleet is powered by E85, a blend of 85% ethanol and 15% petrol.
"In some parts of the country, E85 significantly increased ozone, a prime ingredient of smog," Jacobson says.
Asthma, weakened immune systems and other health conditions have been linked to even small increases in ozone in the atmosphere.
The World Health Organization estimates that 800,000 people die each year from ozone and other chemicals in smog.
E85 could boost US asthma-related emergency department visits by 770 a year and the number of respiratory-related hospitalisations by 990, the study says.
In Los Angeles, there would be 650 more hospitalisations and 1200 more asthma-related emergency visits in 2020 under the E85 model.