There are three basic strategies to improve indoor air quality:
#1 – Source control
Usually, the most effective way to improve indoor air quality is to eliminate individual sources of pollution or reduce their emissions .
Some sources, such as those containing asbestos, may be sealed or closed; Others, such as gas stoves, can be adjusted to decrease the amount of emissions. In many cases,
source control is also a more cost-effective approach to protecting indoor air quality than increasing ventilation, since increasing ventilation can increase energy costs.
#2 – Improvements in ventilation
For most indoor air quality problems in homes, source control is the most cost-effective solution.
Another approach to decrease indoor air pollutant concentrations in your home is to increase the amount of external air entering the interior .
Most home heating and cooling systems, including forced air heating systems, do not mechanically bring fresh air into the home. Opening windows and doors, operating attic or window fans when the weather permits, or starting a window air conditioner with the air outlet control open increases the rate of outside ventilation. Local kitchen or bathroom fans that blow air outside remove pollutants directly from the room where the fan is located and also increase the rate of external air ventilation.
Advanced designs for new homes are beginning to offer mechanical systems that draw external air into the home.
Some of these designs include energy efficient heat recovery fans (also known as air heat exchangers).
For information on whole house ventilation system options, see Energy Saving from the US Department of Energy: Whole House Ventilation.
Ventilation and shade can help control indoor temperatures. Ventilation also helps remove or dilute airborne contaminants in closed spaces that come from indoor sources. This reduces the level of pollutants and improves indoor air quality (IAQ). Carefully evaluate the use of ventilation to reduce air pollutants in confined spaces where there may be nearby outdoor sources of polluting elements, such as smoke or debris.
The introduction of external air is an important factor in promoting good air quality.
Air can enter a house in several different ways, including the following:
- Through natural ventilation, such as windows and doors;
- Through mechanical means, such as external air inlets associated with the heating, ventilation, and air conditioning (HVAC) system;
- Through infiltration, a process by which external air enters the home through openings, joints, and cracks in walls, floors, and ceilings, and around windows and doors.
Infiltration occurs to some extent in all houses.
Natural ventilation describes the movement of air through open doors and windows. If used properly, natural ventilation can sometimes help moderate indoor air temperature, which can become too hot without air conditioning systems, or when power outages or brownouts limit usage. air conditioning or make it impossible.
Natural ventilation can also improve indoor air quality by reducing pollutants found in closed spaces. Examples of natural ventilation are:
- Open doors and windows,
- Close the blinds to get shade
Most residential air conditioning systems and forced air heating systems do not mechanically introduce external air into the home, and infiltration and natural ventilation are used to bring external air into the home. . Advanced designs for new homes are beginning to add a mechanical function that draws outside air into the home through the HVAC system. Some of these designs include energy efficient heat recovery fans to mitigate the cost of cooling and heating this air during the summer and winter.
#3 – Air filters
There are many types and sizes of air filters on the market, ranging from relatively inexpensive benchtop models to sophisticated and expensive whole-house systems. Some air filters are very effective at removing particulates, while others, including most benchtop models, are much less effective. Air filters are generally not designed to remove gaseous contaminants.
The effectiveness of an air filter depends on how it collects indoor air pollutants (expressed as a percentage efficiency index) and how much air is drawn through the cleaning element or filter (expressed in cubic feet per minute ).
A very efficient collector with a low air circulation index will not be effective, and neither
will a filter with a high air circulation index, but a less efficient collector. The long-term performance of any air filter depends on maintaining it in accordance with the manufacturer’s instructions.
Another important factor in determining the effectiveness of an air filter is the power of the polluting source. Tabletop air filters, in particular, cannot remove sufficient amounts of contaminants from nearby powerful sources. People with sensitivity to particular sources may find that air filters are useful only in conjunction with coordinated efforts to eliminate the source.
Over the past few years, some advertisements have suggested that houseplants have been shown to reduce the levels of some chemicals in laboratory experiments. However, there is currently no evidence that a reasonable number of indoor plants remove significant amounts of contaminants in homes and offices. Indoor plants should not be over-watered because overly moist soil can promote the growth of microorganisms that can affect allergy sufferers.
Currently, the EPA does not recommend using air filters to reduce radon levels and their decay products. The effectiveness of these devices is uncertain because they only partially remove radon decay products and do not decrease the amount of radon that enters the home. EPA plans to conduct additional research into whether air filters are, or could be, a reliable means of reducing the health risk from exposure to radon.