What you need to know about air purifiers
You may think that outdoor air is more likely to be polluted than air inside your home, but indoor air is often even more polluted than outdoor air! Air purifiers are supposed to help by removing allergens such as pollen, animal dander, mold spores, and other airborne particles from indoor air. For this reason, air purifiers may be a useful addition to your plan to help reduce symptoms of environmental allergies (allergic rhinitis).
There are various different categories of air purification systems.
If your home has a central heating, ventilation and air conditioning (HVAC) system, this system can be turned into a whole-house filtration system through installation of disposable air filters with a high MERV rating (minimum efficiency reporting value). These filters catch particles such as pollen, pet allergens, and mold, and they can be thrown away when they are full (which occurs about every two months or as recommended by the system).
HVAC systems are beneficial in that they offer the opportunity for whole-house filtration, but the drawback of HVAC systems is that they can actually create a reservoir for triggers and increase the risk of asthma and allergy symptoms if the systems are poorly maintained or contaminated. In fact, dirty filters themselves have the potential to become a source for air contamination and allergens. For example, fungal spores can be trapped, colonized, and released from poorly maintained filters into your household air. Problems such as poor filter fit and duct leakage also have the potential to reduce the effectiveness of filtration.
Individual room air purifiers are another option for air purification in homes without forced air HVAC systems. These devices are more portable and easier to maintain than HVAC systems. While a single device will not filter a whole home, multiple can be used throughout various rooms in the home. The filtration types generally fall into two categories: HEPA filters and electronic electrostatic devices.
Electronic electrostatic devices, also known as ionizers or electronic air purifiers, use electrically charged filters to reduce the number of airborne contaminants in your home. The major benefit of this type of air purifier is that there is no need to periodically replace any filters. However, ionic / electrostatic air purifiers are relatively ineffective when it comes to removing dust, dirt, pollen, dander, and other allergens. Additionally, these purifiers release ozone, which is an irritant, and they force particles to attach to walls or other surfaces. For these reasons, electronic electrostatic devices are not a good choice for people looking to reduce their exposure to allergens.
Using an air purifier
Instead, if you do decide to use an air purifier, make sure that it uses a HEPA (high-efficiency particulate air) filter, which is the most effective at removing airborne particles and allergens from indoor air. Filters are also marked with a CADR (clean air delivery rate), which describes the cubic feet per minute of airflow through the device. Be sure to match the filter’s CADR (clean air delivery rate) with the size of the room where you plan to use the filter. While these filters also need to be replaced, they are generally easier to replace than HVAC filters, and their replacement helps ensure maximum effectiveness.
However, note that while HEPA air purifiers are effective and will not make allergies worse, they are not guaranteed to relieve symptoms and should not be the only steps taken to manage your allergies or asthma. Many allergens such as dust mite droppings do not stay airborne for very long—they tend to settle quickly to surfaces, where air purifiers would be useless in removing their presence. In order to more effectively reduce exposure to environmental allergens, take other measures such as encasing your bedding, closing windows, vacuuming carpets, and changing clothes and showering after being outside on a high-pollen day. Make sure to still include asthma or allergy medication in your plan if needed.
