The kitchen is a place we use numerous time a day, paying relatively little attention to the potentially harmful effects of the smells that are present. More or less pleasant, more or less persistent, these odours are generally perceived as a harmless consequence of cooking and handling ingredients and other products. These odours stem from volatile compounds found in certain substances, which diffuse into the air. Can these molecules be harmful? How can we protect ourselves?
While it is well-known that certain fuels, like charcoal or wood, release toxic substances1, the health impacts of preparing a simple meal, even using conventional combustion methods, remain largely unknown to many. A number of scientific studies have addressed the issue of indoor air pollution in the kitchen, and in this article we propose a few lessons and the best practices to protect your health and that of your loved ones, and limit odour-related discomfort.
An unpleasant smell, coming from road traffic or an industrial site, is often a source of concern. Conversely, the kitchen, with its pleasant smells, is rarely identified as a place where the air is saturated with toxic particles. Yet there is no systematic link between olfactory discomfort and health risk:
Moreover, prolonged or repeated exposure to unpleasant smells can also affect health by causing stress and reducing well-being.
In 2018, researchers at the University of Colorado launched a study to assess the impact of daily activities on indoor air quality2. Among the cases analysed, they tested the pollution emitted by cooking a full Thanksgiving dinner, where vegetables and meats are usually grilled or roasted. First surprise: pollutant concentrations were so high that they had to adjust the settings of their measuring devices!
During the hour following the preparation of the dinner, the level of fine particles, PM2.5, likely to penetrate the respiratory tract, was 200 micrograms/m3, i.e. 5 times higher than that of the city of Paris , and almost identical to that of Calcutta, the 2nd most polluted city in the world! Exposure continues during the post-cooking degradation phase, and may even exceed that of the cooking period itself. Particle levels decrease progressively and, in the study cited, the WHO-recommended threshold of 10 micrograms/m3 was reached after more than 8 hours.
The researchers also modeled the respiratory deposition of particulate matter for an adult staying 12 hours in the kitchen of the test house: it would measure 7 micrograms with no other indoor activity, but could rise to 68 micrograms during a 'typical' day accounting for three meals and the associated clean-up times, to reach 149 micrograms for a simulated Thanksgiving meal2.
Another study3 measured the emissions of fine and ultrafine particles from 33 cooking sessions in Hong Kong homes, using traditional Chinese ingredients and recipes, spread across 12 naturally ventilated ovens. After cooking, the concentration of fine and ultrafine particles was 10 to 40 times higher than it was before, reaching a maximum average of around 160 micrograms/m3 in the kitchen. This pollution peak lasted about an hour and a half. The particles emitted by cooking spread to other rooms in the house, impacting the health of all residents, including children and people with respiratory problems, who might think they are protected from this pollution by staying away from the kitchen when it is in use. Particle levels in the living room reached around 60 micrograms/m3 for an hour. In Hong Kong, it is estimated that the kitchen is responsible for 62% of PM2.5 fine particle pollution within homes.
Fumes from gases, oils, charred ingredients and residue on cooking utensils, as well as particles released during the combustion process, form a mixture that generates kitchen smells and can be toxic. Several factors have an impact on the effects of cooking on health:
Foods with a higher fat content release more pollutants4, with distinctions to be made within these ingredients: not all oils affect indoor air quality in the same way. Despite its pleasant taste and aroma, olive oil releases a significant number of fine particles when heated5.
The cooking method, along with the duration and temperature, can affect air quality; roasting, grilling, or frying tend to release more fine particles, while steaming or boiling is gentler on our lungs and creates fewer kitchen smells.
According to several studies, cooking with gas has a greater impact on indoor air quality than cooking with an electric cooker, even though fine particles are released by both types of appliance. Some American6 and European7 studies even accuse gas cooking of being responsible for over 12% of cases of childhood asthma. In France for example, with approximately one-third of homes using gas stoves, the TNO report7 estimates that 140,000 cases of childhood asthma may be attributable to this cooking method.
Families using gas for cooking exceed the WHO's recommended daily exposure limit for nitrogen dioxide (NO2) on average five days a week. Gas hobs also emit pollutants that are known to cause health effects, such as carbon monoxide and ultrafine particles. Another study8 showed that PM2.5 concentrations in the kitchen exceeded 1000 micrograms/m3 when several gas appliances were used: frying on the stove, sautéing in oil on a burner, or baking lasagna in the oven, with CO concentrations during cooking periods exceeding 9 parts per billion (ppb). NO2 levels exceeded 50 ppb in some tests, and were as high as 400 ppb in an oven cleaning test, exceeding the Air Resources Board's recommendations for indoor air quality standards. Formaldehyde levels were also higher than these recommendations during certain actions such as grilling fish or cleaning the oven.
Indoor air pollution in the kitchen will be greater if ovens, cookers and other appliances are poorly maintained or poorly ventilated. The convenience of self-cleaning kitchen appliances is appealing, but beware of their impact on health! Burning waste produces numerous fine particles, such as NO2, carbon monoxide, and other pollutants, in potentially harmful concentrations.
Of course, natural ventilation and fresh air are essential for limiting indoor pollution, whether in the kitchen or in other areas of your home. But the weather doesn't always lend itself to cooking with the window open! Some helpful practices can improve the air quality in your kitchen and eliminate smells:
These good practices are the essential basis for good air quality and the reduction of kitchen smells, but they are not always enough to deal with the pollution peaks generated by cooking and cleaning. So should you stop cooking? Of course not! But you do need to equip yourself accordingly. To reconcile the pleasure of cooking with the health and olfactory comfort of residents, we recommend installing an air purifier. It will provide the following benefits:
Several air purifier technologies exist. Not all of them work on the same types of pollutants, and you need to take the characteristics of each one into account to make the right choice for your needs. You can read our complete guide to choosing the right air purifier.
Our air purifiers work by generating negative ions, which naturally occur in the environment, to charge and remove pollutants from the air. This perfectly silent technology is effective on 99.9% of polluting particles: urban pollution, viruses, bacteria, allergens, mould, ultrafine particles, dust, smoke, pollen, odours, VOCs, and more. To combat the high levels of pollutants typically found in kitchens, we've developed the ALANA™ air purifier. This supplements particle ionisation with an electrofiltration system: once charged and weighed down by negative ions, the pollutants are pressed against the electrofilters and captured. There are several levels of adjustment, so the air purifier can be adapted to varying conditions throughout the day:
You can find ALANA™ right now on our website. Don't hesitate to contact us to find out more and get all the advice you need to get rid of kitchen smells and improve indoor air quality!
1- According to the Global Centre for Clean Air Research (GCARE), indoor air pollution generated by cooking fuels such as charcoal and wood causes around 4 million deaths worldwide every year.
2- See full report: Indoor Particulate Matter during HOMEChem: Concentrations, Size Distributions, and Exposures, American Chemical Society, 2020: https://pubs.acs.org/doi/10.1021/acs.est.0c00740 or the articles based on it: A hidden source of air pollution? Your daily household, February 2019: https://www.sciencedaily.com/releases/2019/02/190217115857.htm and The Hidden Air Pollution in Our Homes, department of public health, April 2019 https://www.newyorker.com/magazine/2019/04/08/the-hidden-air-pollution-in-our-homes
3- Ultrafine particles and PM2.5 generated from cooking in homes. Atmospheric Environment, 2011. https://www.infona.pl/resource/bwmeta1.element.elsevier-d1f9c262-a5c1-3095-8e6d-77aa496ccd35
4- Source apportionment of indoor PM2.5 and PM10 in homes. Indoor and Built Environment, 2020
5- Emissions and indoor concentrations of particulate matter and its specific chemical components from cooking: A review. Atmospheric Environment, 2013.
6 - Gruenwald, T.; Seals, B.A.; Knibbs, L.D.; Hosgood, H.D., III. Population Attributable Fraction of Gas Stoves and Childhood Asthma in the United States.Int. J. Environ. Res. Public Health 2023, 20, 75. https://doi.org/10.3390/ijerph20010075 Int. J. Environ. Res. Public Health 2023, 20, 75. https://doi.org/10.3390/ijerph20010075
7- TNO Report 2023, Health effects in EU and UK from cooking on gas, https://www.tno.nl/en/sustainable/safe-sustainable-living-environment/energy-built-environment/monitoring-energy-performance/indoor-particulate-matter/
8- Indoor Air Quality: Residential Cooking Exposures, State of California, Air Resources Board, 2001, https://hero.epa.gov/hero/index.cfm/reference/details/reference_id/90689 and https://ww2.arb.ca.gov/resources/documents/indoor-air-pollution-cooking
Natural environments are rich in negative ions. This is precisely the principle on which the air ionizer is based on. However, do you know how this technology manages to capture the pollution particles contained in the indoor air to purify your home?
In December 2019, a respiratory virus of the Coronavirus family appeared in the Wuhan region of China and has now spread to all continents.
Purifying indoor air while protecting your health and the planet is possible! Say goodbye to filters and make way for negative ions: choose an eco-responsible air purifier that will easily reduce energy and resource consumption.