Do HVAC Allergy Filters Really Work?

Air filtration is often recommended as a component of environmental control practices for patients with allergic respiratory diseases. Studies support multiple interventions, including air filtration, as methods to improve outcomes in the treatment of allergic respiratory diseases. Residential air filtration can be provided by Whole Home Filtration (WHF) through the home's Heating, Ventilation, and Air Conditioning (HVAC) system, the Portable Room Air Cleaner (PRAC), or a combination of both. Devices have also been developed to filter the Sleeping Breathing Zone (SBZ).

HVAC systems can create a reservoir for triggers if they are not well maintained. Economical, low-efficiency HVAC filters offer no better particle removal than any other filter. The WHF with high-efficiency HVAC filtration has been proven to be more effective at reducing particles than individual High Efficiency Particulate Air (HEPA) Room Air Cleaners (RACs). A study combining HVAC maintenance with a high-efficiency disposable Minimum Efficiency Reporting Value (MERV) 12 HVAC filter has demonstrated the clinical benefit of WHF in asthma.

A PRAC HEPA study tends to yield clinical benefits, but its effectiveness is limited to a single room and not the entire home. Multiple rooms are needed to approach the benefit of high-efficiency WHF. Ionic electrostatic air cleaners provide little or no benefit compared to PRAC, WHF or HEPA. Ionic devices produce ozone, a respiratory irritant, and in a study caused an increase in submicron particles.

Three clinical studies demonstrated that SBZ filtration was effective. The best and most cost-effective approach may be to consider “combination filtration” using high-efficiency WHF with PRAC or breathing zone filtration in the bedroom. If you're plagued by allergies and have done everything you can to reduce allergens in your home, an air filter could help. People with lung diseases such as emphysema or Chronic Obstructive Pulmonary Disease (COPD) might also consider buying an air filter, says Paul Enright, MD, research professor of medicine at the University of Arizona.

But if you're a healthy person living in a relatively unpolluted environment, there's no need to spend the money. Just remember, Enright says, that an air cleaning system is just one of the environmental changes you can make to relieve symptoms. There is no single adequate response to dealing with allergies and asthma. Increasing filter efficiency above American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) (65% to 85%) (MERV 11—1) to a HEPA filter did not significantly reduce indoor concentrations.

If your home has ducted heating or air conditioning, it's possible to add filters to your air handling system. As air moves through the filter, contaminants and particles are captured, and clean air is returned to the living space. A trained professional can recommend adaptations to compensate for the consequences of airflow and pressure from a high-efficiency filter and to keep the HVAC system operating efficiently over time. The primary purpose of a heating and air conditioning filter is to prevent dust and dirt from clogging the unit.

These filters are usually cheaper than other mechanical filters such as HEPA because coarse-grated fibers are easier to manufacture. Electrostatic air filter units remove many airborne particles of a given size, under the right conditions. However, the Molekule air purifier may be a better long-term investment, as it can eliminate harmful gases in addition to particulate pollution and removes allergens such as mold so it never grows in a filter. Depending on your budget and your particular allergies, a HEPA filter or a Molekule device may be a viable option to reduce allergen levels in the air.

The Environmental Protection Agency (EPA) and the American Lung Association recommend air filtration for people with allergies and asthma, but not as a solution on its own. Learn the facts about choosing the right air filters for allergies, as well as other HVAC maintenance tips that can reduce your suffering this season. Many homeowners also purchase filters for their air quality enhancing properties, making them a must-buy for allergy sufferers. The next time you buy an air filter in a large store or online, take a moment to look at the specifications.

To account for these pressure-related differences, talk to a professional HVAC technician about compensating for a high-efficiency or high-MERV filter.