Does Burnt Toast Pollute the Air?

An alarming new study from the University of Austin in Texas, USA has revealed that burning a piece of toast in your kitchen could expose you to more pollution than standing outside at a busy traffic intersection. The authors of the paper arrived at their findings by building a fake three-bedroom house and equipping it with sophisticated airborne molecular contamination sensors to understand how a range of everyday tasks affected air quality levels around the home.

While other mundane household items like cleaning products, scented candles and aerosols were also guilty of upsetting the quality of indoor air, the biggest shocks were reserved for the impact of the toaster. Even just switching it on creates pollution around the home, the researchers found, while burning a slice of bread could create concentrations of particulate matter (PM) that are 120 times higher than the safe limit as recommended by the World Health Organisation (WHO).

Golden, not brown

The scientists behind the study said that the safest way to toast bread was to aim for a uniform golden finish, without any darker discolouration. However, even making golden toast could result in PM concentrations of over 300, which is 12 times the recommended upper threshold of 25 as designated by the WHO.

In fact, just switching the toaster on in the first place already creates unwanted contamination, since the heating elements can come into contact with crumbs of bread and other debris that have become lodged at the bottom of the appliance. This in turn creates smoky fumes and leads to the emissions of a range of contaminants, including ethanol and PM.

Actually burning toast is a massive no-no, since PM concentrations can surpass 3,000. That’s 120 times the recommended upper threshold and 7.5 times higher than the highest concentrations recorded in central London last year. But while there are official European and international standards pertaining to indoor air quality in the workplace, domestic airwaves are not regulated.

Indoor air the silent killer

The dangers of prolonged exposure to poor air quality in megacities like Beijing, New Delhi and even London is well-documented; it’s thought that almost 10,000 people in the UK capital and 50,000 across the entire nation lose their lives to air pollution each year. Indoor air quality, on the other hand, flies comparatively under the radar.

As well as burning toast, frying and roasting food without the use of an exhaust hood and with doors and windows closed is also a major generator of harmful indoor fumes. Wood-burning stoves are another chief culprit, with scented candles, aerosols, cleaning agents and, ironically, air purifiers which carry a fragrance also guilty of compromising air quality.

Indoor air pollution is believed to be so dangerous because of the confined nature of a home environment. Once contaminants find their way into the atmosphere, there is no place for them to go, so they continue to be inhaled and ingested by the humans, animals and plants living in their vicinity. The authors of the report hope that it will raise awareness not only on the dangers of toasting bread, but around indoor air quality in general.