When Should I Worry About...

Can Forgetting to Replace Your Air Filter Impact Your Health?

June 15, 2020 - Katie McCallum

There are a lot of chores to keep up with around your home, and changing the air filter is probably one of the easiest to forget.

In some homes, the air filter is out of sight — which then easily turns into out of mind. In other homes, the air filter may be tough to reach. Most of the time, though, changing your air filter probably just seems like one of those inconsequential chores that's okay to put off.

Regardless of why it happens, you may be wondering if forgetting to regularly change your air filter is really that big of a deal.

Aside from the detrimental effects a dirty air filter can have on your A/C system itself, could forgetting to replace your air filter also be detrimental to your health?

Why does indoor air quality matter?

Just as the air quality outdoors affects your health, there's growing evidence that indoor air quality can, too.

There are a number of pollutants and irritants that can end up circulating in the air inside your home, including:

  • Pollen
  • Pet dander
  • Dust
  • Molds, bacteria and viruses
  • Vehicle exhaust
  • Emissions from smoking or cooking


Airborne particles come in a range of sizes, most of which you can't actually see. Particles smaller than 10 microns — such as the ones mentioned above — are easily inhaled. These particles have the potential to irritate your eyes, nose and throat and affect both your lungs and your heart.

According to the Environmental Protection Agency (EPA), the three most effective ways to reduce airborne particles in your home are by:

  • Removing the source of the particles: Regularly cleaning and dusting surfaces, brushing your pet outdoors, not smoking inside your home and eliminating any potential for moisture buildup.

  • Ensuring proper ventilation: Using properly installed exhaust fans while cooking or using household cleaning products.

  • Air cleaning: Using a medium-to-high efficiency air filter and replacing it regularly, or adding an air purifier to a commonly used space in your home.

Can an air filter actually improve your home's air quality?

You probably already know that an air filter helps prevent dust accumulation in the inner workings of your A/C unit. But does an air filter also help clean the air you breathe throughout your home?

According to the EPA, yes — air filters can help remove and reduce airborne particles in your home, including the ones that are of greatest health concern.

But, not all air filters are created equal. Some are better at cleaning the air in your home than others, and a rating called MERV (which stands for Minimum Efficiency Reporting Value) can help you understand the effectiveness of each air filter option you run across.

The higher the MERV, the more particles an air filter can actually remove from the air. Filters with a MERV of 4 or below help protect your A/C system, but are not effective in cleaning the air in your home.

The EPA reports that air filters with MERVs between 7 and 13 are your best bet for removing some of the airborne particles that cause the greatest health concerns.

Most residential homes can accommodate air filters up to MERV 13, but you may want check with a professional HVAC technician before using anything over MERV 9. Going beyond what your system can handle will result in reduced performance and, ultimately, unwanted costs and strain on your system.

No matter how efficient (or inefficient) your air filter is, here are four other key points to keep in mind:

  • A dirty air filter won't work as well as one that's properly maintained. This means you'll need to replace the filter often, as recommended by the manufacturer.

  • An air filter can only clean the air in your home while it's being used. If your A/C system isn't on, your air filter isn't cleaning your household air.

  • An air filter can only remove airborne particles it comes into contact with. Your air filter won't be able to remove particles that have already settled on surfaces around your home, and it's not as effective if household air is not adequately being sucked into your air return.

  • No air filter will completely clean the air in your home. An air filter can reduce the amount of airborne particles in your home, but it cannot remove all of them. This is why it's also important to also reduce sources of allergens and ensure proper ventilation.

Can regularly replacing your air filter help alleviate allergies or asthma?

If you have bad allergies or asthma, you likely tried everything to reduce your symptoms. This means you may be way more diligent about remembering to replace your air filter regularly — but is it really improving your symptoms?

A 2014 study reports that using a MERV 12 (or higher) air filter does reduce the levels of particles known to commonly trigger asthma or allergies.

But does this actually translate into improvements in your symptoms?

Well, this is still sort of unclear. While some studies say yes, others say no — while still more say some symptoms are improved, but not others.

Several studies do show, however, that a very efficient type of air filter, called a HEPA filter, may help reduce allergy or asthma symptoms. But these improvements are modest. And, before you go out and try to buy a HEPA air filter, know that most residential A/C units cannot accommodate this type of filter without making some pretty expensive upgrades to your system. Plus, the EPA states that some MERV 12 filters and most MERV 13 filters are almost as effective as HEPA filters in reducing the airborne particles linked to adverse health effects.

So, what should you do if you have asthma or allergies? The EPA recommends that people concerned about their symptoms choose an air filter with as high a MERV as the A/C unit can handle — with a MERV 13 air filter being most ideal.

Overall, there's a lot to consider about air filters and your health. When it comes to improving the air quality in your home, here are four key takeaways:

  • You must regularly replace your air filter(s), according to the manufacturers instructions, and run your A/C — or blower fan, at the very least — often.

  • Relying on air filtration alone is not enough — you must also take steps to remove the source of household allergens, as well as ensure proper ventilation in your kitchen and bathrooms.

  • An air filter with a MERV of 4 or less will protect your A/C unit from airborne particles, but will not improve your indoor air quality.

  • If you have asthma or allergies, you may want to consider purchasing an air filter with the maximum MERV your A/C unit can handle.
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