Eat out to help out' scheme added to air pollution in London, study finds

"Looking in more detail, Chen saw that soot from diesel exhaust was lower than the previous August, suggesting changes to traffic were not the cause. The chemical fingerprints of the particles provided the first explanation. They contained fatty acids from cooking, but their timings did not match the usual pattern of lunch, evenings and weekends. Instead, the pollution peaks happened each evening Monday to Wednesday, when the eat out to help out scheme operated."

"There was another pollution source on those summer evenings. It contained chemicals that are normally seen from wood stoves in winter, but it was August and warm. Chen said: We normally only detect the emissions from frying food, but here we were able to link these with cooking fuels, like wood and charcoal. This was the hardest part of the project and had never been observed before."

Eat Out to Help Out subsidised restaurant and pub meals three days a week in August 2020 to reboot the hospitality sector. Monitoring on Marylebone Road recorded unusual evening pollution peaks Monday–Wednesday that matched the scheme's schedule. Diesel soot was lower than the previous August, so traffic changes did not explain the peaks. Chemical fingerprints showed fatty acids from cooking and compounds typical of wood-stove emissions, implicating commercial cooking fuels such as wood and charcoal. The pattern persisted into September and October, indicating lasting behavioural effects. Commercial cooking emissions are often overlooked in air pollution control.

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