Kitchen and Bathroom Fans, a Simple Home Ventilation Routine

For most indoor air problems at home, EPA says the most effective fix is usually source control: remove or reduce the thing releasing the pollutant. Ventilation comes second. Fans that exhaust outdoors from the kitchen and bathroom, plus open windows during high-pollution tasks, are the practical part of a weekly routine.

1. The three strategies

EPA lists three basic strategies (it calls source control usually the most effective):

1. Source control. Eliminate individual sources of pollution or reduce their emissions. Some sources can be sealed or enclosed, and others, like gas stoves, can be adjusted to reduce emissions.
2. Improved ventilation. Bring in more outdoor air.
3. Air cleaners and filtration.

EPA also points out that source control is often cheaper than extra ventilation, because more ventilation can raise energy costs.

2. Why a home can have a ventilation problem

EPA explains that if too little outdoor air enters, pollutants can build up. Buildings designed to minimize outdoor air leakage may have higher indoor pollutant levels unless they have special mechanical ventilation. High temperature and humidity can also increase the concentration of some pollutants.

Air enters a building three ways: infiltration (through cracks, joints and openings), natural ventilation (open windows and doors) and mechanical ventilation. Most home heating and cooling systems, including forced-air heating, do not bring fresh air in mechanically.

3. What EPA says to do

• Open windows and doors, or run window or attic fans, when the weather permits.
• Run a window air conditioner with the vent control open.
• Use bathroom and kitchen fans that exhaust outdoors. EPA says these remove contaminants directly from the room where the fan sits and also increase the outdoor air ventilation rate.

EPA says to take as many of these steps as possible during short-term activities that create high pollutant levels, including painting, paint stripping, heating with kerosene heaters, cooking, and hobbies such as welding, soldering or sanding. If weather allows, some of those jobs can be done outdoors.

EPA adds one caution: carefully evaluate using ventilation where outdoor sources, such as smoke or refuse nearby, may be a problem.

4. Common home sources EPA names

The agency's list of indoor pollution sources includes fuel-burning combustion appliances, tobacco products, newly installed flooring, upholstery or carpet, certain pressed-wood cabinets and furniture, household cleaning and maintenance products, personal care and hobby products, central heating and cooling systems and humidification devices, and excess moisture. Outdoor sources include radon, pesticides and outdoor air pollution.

Maintenance counts, too. EPA's example: an improperly adjusted gas stove can emit significantly more carbon monoxide than one that is properly adjusted.

5. A weekly ventilation routine built from that advice

While cooking: turn on the range hood or kitchen fan if it vents outdoors, and open a window when weather allows.

After showers: run the bathroom fan. Excess moisture is on EPA's source list, so removing it is source control and ventilation at once.

Before cleaning or hobby work: open a window first, particularly for painting, sanding or soldering.

Once a week: check that fans actually run, and that you know where each one vents. EPA's text refers to local fans that exhaust outdoors, so confirm yours does not just discharge into an attic or ceiling space.

Monthly: read the manuals for any gas or fuel-burning appliance to see what the maker says about adjustment and servicing, since EPA notes a gas stove can be adjusted to cut emissions. EPA says that in some cases a source's age and whether it is properly maintained are significant factors.

6. What does not substitute for ventilation

Air cleaners are not a universal fix. EPA says they are generally not designed to remove gaseous pollutants, and that while some are highly effective at removing particles, most table-top models are much less so. Their effectiveness depends on how well they collect pollutants and how much air they move, and they must be maintained according to the manufacturer.

On plants, EPA is blunt: there is currently no evidence that a reasonable number of houseplants remove significant quantities of pollutants in homes and offices. Overwatering can promote growth of microorganisms that affect allergic people.

7. When to take symptoms seriously

EPA notes that immediate effects of indoor pollutants include irritation of the eyes, nose and throat, headaches, dizziness and fatigue. If symptoms fade when you leave an area, that is a clue to look for an indoor source. Symptoms can resemble a cold, so pay attention to when and where they occur.

8. Key takeaways

• EPA lists source control, ventilation and air cleaners as the three strategies, and calls source control usually the most effective.
• Outdoor-vented kitchen and bathroom fans remove pollutants at the source and raise the outdoor air rate.
• Ventilate most during cooking, painting, sanding and similar tasks.
• Appliance maintenance matters; a poorly adjusted gas stove can emit far more carbon monoxide.
• Table-top air cleaners and houseplants should not be the main plan.