Why your roast dinner could be killing you: Indoor pollution from cooking as bad as in city centres, say scientists

Families should boil rather than roast their Sunday lunch to avoid indoor pollution levels worse than the most toxic cities on Earth, scientists have said.

New research is showing that preparing the traditional meal with the windows shut gives readings up to 13 times worse than in central London on a congested day.

The world’s largest gathering of scientists heard that pollutants from roasting include PM2.5 particulates, which are particularly harmful because they are small enough to embed deep into the lungs and, in some cases, even enter the bloodstream.

Experiments during Thanksgiving in the US found that cooking a full roast turkey dinner pushed readings to peak levels of 200 micrograms per cubic meter (m/cm).

The World Health Organization safety limit for PM2.5 particulates is 10 m/cm, although central London averages 15.2.

The research team said that roasting vegetables contributes badly to indoor pollution levels badly because cooks often aim for a charring or blackening effect. They singled out Brussels sprouts as particularly harmful because of how quickly the vegetables blacken when roasted.

While boiling both meat and vegetables would still emit PM2.5, doing so is healthier for the internal atmosphere of a house than roasting, the scientists said.

Professor Marina Vance, who led the research at the University of Colorado Boulder, said: “We were all surprised at the overall levels of particulate matter in the house. “It compares to a very polluted city."

She added: “The joke we’ve been telling ourselves as scientists is boil everything, avoid roasting, but it’s too delicious.”

The researchers cooked a series of meals in a three-bedroom house fitted with indoor and outdoor pollution monitors.

For one of the experiments, they cooked a Thanksgiving dinner with roast turkey, roast Brussels sprouts, boiled sweet potatoes, bread stuffing and cranberry sauce. During that, PM2.5 levels in the house rose to 200 micrograms per cubic metre for one hour, more than the 143 micrograms per cubic metre averaged in Delhi, the sixth most polluted city in the world.

“We know that inhaling particles, regardless of what they’re made of, is detrimental to health,” said Professor Vance. “Is it equally bad as inhaling exhaust from vehicle emissions? That we don’t know that yet.”

The research, presented at the American Association for the Advancement of Science annual meeting in Washington DC, forms a broader package of new data on the dangers of common household activities for indoor pollution.

The team warned of further evidence that chemicals involved in cleaning, as well as flame retardants and even vinyl flooring contribute to a toxic indoor atmosphere.

The University of Colorado scientists said that volatile organic compounds (VOCs) from products such as shampoo, perfume and cleaning solutions eventually escape outside and contribute to ozone and fine particle formation, making up an even greater source of global atmospheric air pollution than cars and trucks do.

"Many traditional sources like fossil fuel-burning vehicles have become much cleaner than they used to be," said Professor Joost de Gouw, from the Cooperative Institute for Research in Environmental Sciences.

"Ozone and fine particulates are monitored by the EPA, but data for airborne toxins like formaldehyde and benzene and compounds like alcohols and ketones that originate from the home are very sparse."

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