How do I know if my air purifier filter is dirty?

Author: Alvah Schoen  |  Last update: Saturday, November 29, 2025

How Do I Know if My Air Purifier Filter is Dirty? First, take a look at the filter. If it appears grey or black with dust and debris, then it's time for cleaning or a change depending on the type of filter. Another sign that your air purifier filter is dirty is the reduced efficiency of the purifier.

What happens if you run an air purifier with a dirty filter?

Dirty Air Filters Reduce Airflow, Increasing Strain on Your Blower Fan. Blower fans are designed to push air through the filter. If the filter becomes too clogged with dust, dander and debris, then the blower has to struggle harder to pass the air through the blocked filter.

What does a dirty air filter look like?

A filter that is clogged with dirt is an obvious sign of a dirty air filter. Performing a visual inspection is an easy way to know if your air filter needs to be changed. A brand new air filter is white or off-white in color, while a dirty air filter will appear darker with the dirt and debris visible.

How to tell if an air purifier filter needs replacing?

You see more pet dander moving around. Your air purifier is making unusual noises. Your air purifier doesn't seem to be working properly. The filter looks gray and dirty when you check it.

What does a dirty HEPA filter look like?

If you see a visible buildup of dust or particles on a HEPA filter (it may look gray or dirty) or observe reduced airflow through your portable air purifier, you may assume that's an indication the HEPA filter needs cleaning. However, experts say HEPA filters should always be replaced rather than cleaned.

How To Clean Air Purifier Filters (HEPA - Levoit)

How to tell if an air purifier filter is dirty?

First, take a look at the filter. If it appears grey or black with dust and debris, then it's time for cleaning or a change depending on the type of filter.

Can I clean my air purifier filter instead of replacing it?

Most air purifiers have a pre-filter, HEPA filter, and sometimes an activated carbon filter. You can wash, dry and reuse most pre-filters and carbon filters, but you'll need to buy a replacement HEPA filter from time to time.

How do I know if my air filter is bad?

Thankfully, you can determine whether your air filter needs to be replaced by looking for several signs below.
  1. Reduced Gas Mileage. ...
  2. Strange Engine Noises. ...
  3. Decreased Performance. ...
  4. Check Engine Light Comes On. ...
  5. Black Smoke or Flames in the Exhaust. ...
  6. The Smell of Petrol in the Exhaust. ...
  7. Your Engine Misses or Misfires.

How do I test my air purifier?

To test a whole-home air purifier, you must make the space smell. Cook the smelliest food you can think of, let the wet dog indoors, or burn potent incense that produces a noticeable odor. Then, turn the HVAC system fan on and notice as the odor dissipates. That is proof the air purifier is working.

How long to run an air purifier in a bedroom?

This is why most manufacturers will recommend you to leave your air purifier running all day, especially if it comes equipped with an automatic setting. This setting allows your device to monitor the quality of your air in your home for you and to adjust its speed depending on the levels of pollutants that it detects.

How to tell if a filter is too dirty?

9 Signs of a Dirty Air Filter
  1. Your Air Filter Is Old. ...
  2. It Looks Dirty. ...
  3. It's Affecting Your Indoor Air Quality. ...
  4. It's Causing Bad Allergies. ...
  5. It's Making Your House Dusty. ...
  6. It's Impacting Your Energy Bills. ...
  7. It's Putting a Strain on Your HVAC System. ...
  8. It's Causing Your HVAC System to Overheat.

What color is a bad air filter?

A brand-new air filter, or at least one in good condition, should be relatively clean. Fresh filters feature a white or off-white color, while older filters may be darker in color due to all the dirt and debris they've collected. If your filter looks dark or off-color, bring in a mechanic to check it out just in case.

Can a dirty air filter make you cough?

If you're suffering from an AC cough, there are several cures that you can try. One of the most important things to do is to replace the air filter regularly, as dirty filters can lead to irritation and coughing.

Is no air filter better than a dirty one?

Is no AC filter better than a dirty one? No. A dirty filter will slightly protect against some dust particles that will damage your AC system. Its better to have a dirty filter than having no filter.

Can I wash air purifier filter with water?

You can rinse the filter in water, tap excess dust off of it or remove some dust with a vacuum, but this can definitely damage the mesh of fibers that allows the filter to remove particles from the air. Even if the filter looks undamaged, some of the fibers will be broken or stretched out.

What happens if I don't change the filter in my air purifier?

If you let this happen for long enough, the filter could break, releasing all of the pollutants it has accumulated. The pollutants will then float freely though your HVAC system, your house, and eventually your lungs. This can lead to your home's air supply feeling stuffy and dirty, and you could get sick as a result.

How do I know if my air purifier filter needs replacing?

If you notice a decrease in the air purifier's performance, it could be a sign that the filter is clogged and needs to be replaced. Decreased airflow or reduced effectiveness in removing odors are common indicators.

Why does my air purifier feel like it is not working?

Therefore, when you notice your purifier controls not responding, first check the power cord and make sure it's plugged in properly. If that doesn't work, check the filter cover, fix it correctly, and put the purifier back on. In other instances, the source of the insensitive controls could be faulty controls.

How long should an air purifier last?

That's a minimum number, and means the purifiers would run a minimum of 4-5 years if running them for 6 hours per day. Typically, the motors last much longer. We've seen Smart Air purifiers in use 7 years after they were purchased, still working without issue.

How do I know if my filter needs to be changed?

Signs Your Furnace Filter Needs Changing
  1. There is noticeable discolouration on the filter.
  2. You can see the buildup of dirt and dust.
  3. You find your home needs dusting frequently.
  4. It seems your HVAC system is cycling longer.
  5. You realize it's been several months since you've replaced your filter.

What does a dirty air filter sound like?

Your vehicle's engine may begin to make strange sounds, aside from the sounds that are caused by misfiring. These may be wheezing sounds or coughing sounds. These sounds are caused by an engine air filter that is clogged and is not letting enough air into the vehicle's engine.

What happens if you don't clean your air filter?

Unkempt air filters may negatively affect indoor air quality by spreading pet dander, dust, and other allergens throughout your home. This may lead to irritated eyes, nose, and potentially breathing problems.

Can I just vacuum my air purifier filter?

Wash your HEPA filter with warm water and allow it to dry if your model specifically states that water cleaning is safe. You can also soak your filter in hot water if it is extremely dirty. Clean non-washable, permanent HEPA filters using a vacuum to remove dust and debris.

What happens if air purifier filter is dirty?

Reduced Indoor Air Quality: A Breeding Ground for Health Issues. One of the most immediate and concerning effects of dirty air filters is the decline in indoor air quality. As filters become clogged with dirt, dust, and other particles, they are less effective in capturing and trapping contaminants.

Can you clean an air filter without replacing it?

Cleaning the air filter only improves its appearance. When should an air filter be replaced? The air filter should be replaced after the period indicated by the vehicle manufacturer.

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