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Kitchen air quality and ventilation

The kitchen is the heart of a home. It is a center of activity, a space where families and friends gather to prepare meals and spend time together. But without adequate ventilation, the kitchen can be deadly.

Three billion people worldwide still cook in homes with open fires and little or no ventilation, according to the World Health Organization (WHO). Exposure to indoor pollutants in these homes causes 4.3 million premature deaths every year due to pneumonia, heart disease and other illnesses, according to WHO. It’s a tragic and frightening reminder of the inherent dangers of indoor cooking and of the importance of adequate kitchen ventilation.

Modern kitchens are pollution factories

Inadequate kitchen ventilation isn’t a problem only in developing nations. A study conducted by the Lawrence Berkeley National Laboratory (Berkeley Lab) found that 60% of U.S. homes with gas stoves exceed legal outdoor pollution levels.

The combustion from gas stoves produces nitrogen dioxide, formaldehyde and carbon monoxide. Electric stoves produce the same pollutants, in lower levels. What’s more, electric burners, in particular, produce high levels of ultrafine particles that are easily inhaled, deposited into the lungs and absorbed into the blood. In addition, foods that are cooking produce gases and particles similar to those emitted by the burners.

The kitchen range hood is designed to help

In a modern kitchen, fumes generated by cooking are supposed to be captured and exhausted by a “range hood” over the stove or cooktop. The range hood is a device containing a mechanical fan in a canopy or housing that captures airborne grease, smoke, fumes, odors, heat and steam from the cooktop.

While range hoods are a good idea in theory, studies show that many range hoods don’t function very well. Berkeley Lab found that some range hoods capture as little as 14% of pollutants generated by cooking.

Problems with range hoods

There are three problems that limit the effectiveness of a kitchen range hood:

  1. Wrong size. Many hoods aren’t large enough to cover the front burners on the cooktop above which they are installed. Another problem is range hoods are often placed too high.
  2. Wrong fan. An effective range hood should move at least 340 cubic meters of air per hour (m3/h). However, a fan that is too powerful (some popular models are rated well over 1529 m3/h) may create backdrafting of carbon monoxide and other gases from furnaces, water heaters and other appliances in the home. These powerful range hoods require a “makeup air” system that adds fresh air back into the house to prevent backdrafting.
  3. No exhaust. So-called “recirculating” range hoods simply vent the air right back into the room instead of exhausting pollutants outside. Also known as “ductless” systems, these range hoods may contain a replaceable charcoal or metal filter but offer little protection against most pollutants.

Tips for selecting the right range hood

By choosing the right range hood and using it properly, you can dramatically improve the indoor air quality throughout your home. Here are a few tips:

  • Look for a range hood that covers the entire cooking surface. A range that is 7.5-15 centimeters wider than the cooktop will allow for extra coverage and protection.
  • Shop for a fan that is powerful, but not too powerful. If possible, avoid oversized hoods that can generate up to 1529 m3/h and cause backdrafting, unless a makeup air system is being installed.
  • Choose a hood with a hollow shape for collecting smoke and gases as they are released. Combined with outside exhausting and the right fan efficiency, this will dramatically improve the capture rate.

A few simple cooking techniques will also help improve the air quality in your kitchen. Whenever possible, cook foods over the back burners. This is because range hoods offer greater coverage in the back. Also, always be sure to turn the range hood fan on when cooking.

By installing and using the right range hood and by cooking over the back burners whenever possible, your kitchen can be a source of culinary pleasure instead of indoor air pollution.

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