On Christmas Day in 1879 the combination of fog and smoke was so dense over London that it was virtually dark at noon. Nowadays, with many people staying at home and fewer vehicles on the road, the ambient air quality on Christmas Day is typically very good. However air in the home may be at its worst.
On Christmas, indoor sources of air pollution can generate particles that, in terms of number and mass concentrations, significantly exceed background levels. Here are a few reasons why.
Cooking the traditional Christmas dinner can result in elevated levels of a number of pollutants. Ultrafine particles (UFP) smaller than 100 nanometres are of special interest from a health perspective, since they can penetrate deep into the respiratory system and cause inflammatory effects. A number of studies have reported increased UFP concentrations associated with electric stoves and cooking utensils, perhaps from heating detergent residues.
The number of particles emitted during cooking depends upon factors such as the raw food composition, cooking temperature and style – stirring food has been shown to produce larger aerosols as the ingredients are splashed about and tiny specs fly into the atmosphere.
Sergey kamenskykh / shutterstock
Gas cooking is a major source of both nitrogen dioxide (a harmful gas) and particulate matter (tiny, often hazardous particles suspended in the air). Kitchens with gas cooking can have higher levels of nitrogen dioxide than even a busy roadside.
In fact it has been shown that gas cooking is associated with increased risk of both current and lifetime asthma.
The health risks associated with cooking are poorly understood, although UK regulations require extractor fans in kitchens. Given that it takes more than four hours to prepare and cook the average Christmas dinner, people with asthma or cardiovascular disease may want to avoid the kitchen. When cooking, especially with gas, it is important to keep the extractor fan on or open a window.