Here are the most commonly asked questions and their answers about air purifiers.

air purifiers FAQ

Q. What is an Air Purifier?

A. An air purifier is a device which cleans the air from a closed space by removing airborne pollutants.

Q. Air Purifiers are different from Air Cleaners?

A. No, Air Purifiers or Air Cleaners are the same things whose primary goal is to clean the air. There are different types of air cleaning technologies which are used by air-cleaning devices. (Source: EPA Handbook)

Q. How does an air purifier work?

A. Air purifier draws the air using a fan and passes it through its filter(s) or cleaner to purify the air. Some air purifiers don’t require a fan, and they are less effective.

Q. What are the air cleaning technologies?

A. A widely used technology is the use of a fibrous filter to absorb contaminants. Other methods are electrostatic precipitation (ESP), use of absorbent substances, ultraviolet germicidal irradiation (UVGI), ion generation, ozone generation, plasma wave, etc. An air purifier may have a single or multiple air cleaning technologies. Read our article on Conventional Air Cleaning Technologies.

Q. How different air cleaning technology works?

A. Check out the table below about different mechanisms of air cleaning:

Q. What is HEPA Air Purifier?

A. An air purifier that uses HEPA filter as its primary air cleaning method is known as HEPA Air Purifier.

Q. What is HEPA stands for?

A. HEPA stands for High-Efficiency Particulate Air. A HEPA filter is made of different kind of fibers. It is designed to capture particles with greater efficiency. A HEPA filter can remove more than 99% of fine particles which are sizes down to 0.3 microns in diameter.

Q. What is PM2.5?

A. PM2.5 stands for Particulate Matter with a size of 2.5 microns in diameter. It can be solid particles or liquid droplets in the air.

Q. What is the activated carbon filter?

A. The activated carbon filter is made of a thick layer of activated carbon, which absorbs gases and volatile organic compounds (VOCs) from the air. It helps to reduce various types of odors. It is also known as the activated charcoal filter.

Q. What are the pre-filters?

A. Pre-filters are used to capture large particles from the air before it moves through the core filters. It increases the efficiency of the primary HEPA and carbon filter. Most of the cases, pre-filters are washable, and their replacement cost is much less than the central filters.

Q. What is CADR of an Air Purifier?

A. CADR stands for Clean Air Delivery Rate. It expressed as cubic feet per minute (CFM). For a specific sized room, the larger CADR means greater effectiveness for an air purifier. Current CADR standard rated only for particle pollutants. Calculate the exact CADR you needed with our personalized CADR Calculator for air purifier.

Q. What is the CADR rating by AHAM?

A. The Association of Home Appliance Manufacturers (AHAM) certifies 3 CADR value for air purifiers, which are CADR for tobacco smoke, pollen, and dust. You can see it on the packaging label if the device is AHAM verified.

Q. What is ACH for an Air Purifier?

A. ACH or ACPH stands for Air Change Per Hour. ACH is how frequently an air purifier can clean the air from a specific sized room in an hour. For example, 4 ACH for 500 square feet size room means it filters the air of that room 4 times per hour, or it requires 15 minutes to clean the air from the entire room. If you increase the room size, then you will get lower ACH and vice versa. Calculate the required air exchange rate with our advanced ACH calculator to choose an air purifier.

Q. Is it safe to use air purifiers?

A. HEPA air purifiers are entirely safe to use. Those air purifiers which uses plasma or ionizer generate some harmful byproducts like ozone, carbon monoxide. Most of the cases these methods are optional, and they produce ozone at a safe rate.

Q. Which air purifiers are harmful?

A. Intentional ozone generators are unsafe to use in a residential space as air cleaners. If any air purifier generates a high amount of ozone, then it can be harmful as ozone is poisonous for lung.

Q. What are the benefits of air purifiers?

A. Air purifiers can benefit the people who suffer allergy, asthma or have any breathing difficulties. It also helps where the air is contaminated with a high amount of pollutants like smoke or chemical and where the source controls are barely impossible. Read our blog post on The Top 5 Benefits of Air Purifier.

Q. How often to change air purifier filter?

A. You usually need to replace the HEPA filter in 6-12 months based on usage. Carbon filters get saturated quickly, and they may need to replace earlier than the HEPA filter. It also varies from manufactures and air purifier models. Almost all air purifier has a filter life indicator.

Q. Does air purifiers help to reduce moisture?

A. No, air purifiers do not control the moisture in the indoor air.

Q. Does air purifiers help to reduce mold growth?

A. No, air purifiers do not help to reduce mold growth. However, it removes the mold spores from the air. You need to control indoor humidity level to minimize mold growth.

Q. How much electricity used by an air purifier?

A. An air purifier does not require much energy to operate. Most of the power needs to run the fan which circulates the air. A mid-range air purifiers power consumption is about 50W on average.

Q. Can I run the air purifier all night?

A. Yes, you can. Most of the air purifiers have an automatic mode. They operate based on indoor air quality, which is energy efficient.

Q. How much the filter replacement cost?

A. It varies from brand and models. Normally, an air purifiers annual filter replacement cost is around $60-$70 on average.

Q. How much noise an air purifier produces?

A. An air purifier has multiple fan speed settings. On higher speed mode you will get much noise, and they run quieter on the lower fan setting. However, it varies from manufacturers and models.

Q. Can I run the air purifier with windows open?

A. Yes, you can, but it will decrease the effectiveness of the air purifier.

Q. Which air purifiers are best?

A. True HEPA based air purifiers are best in performance.

Q. What should I need to check before buying an air purifier?

A. At first check, the filter is true HEPA, not any cousin of HEPA filter. Then check the CADR and ACH for your room size. Occasionally you can check its portability, noise level, automatic mode, fan speed, filters lifespan, filter replacement cost, usability, AHAM rating, energy star rating, etc.

Q. What should I need to check to buy an air purifier for allergy?

A. For an allergy sufferer, you need at least 3 air changes per hour (ACH) for your room. Also, check the noise level because you may need to run the air purifier overnight. The air quality sensor should be good for smooth operation.

Q. What should I need to check to buy an air purifier to remove smoke and odor?

A. For removing smoke effectively, you need at least 5 air changes per hour (ACH). Also, you must need an air purifier which included an activated carbon or an activated alumina filter to remove the smell from smoke. Here is our reviews on Top 9 Air Purifiers for Smoke you can read.

Q. What should I need to check to buy an air purifier to remove volatile organic compounds (VOCs)?

A. A thicker layer of activated carbon filter will help to absorb the VOC gases. Plasma wave or UV lights are also useful to remove gases. You can choose one with the following filter combination to get greater effectiveness.

Q. Where should I place an air purifier?

A. Place the device where it can easily intake and flow the air. Always make sure that nothing can block its airflow.

Q. How do I know my air purifier is working?

A. Most of the air purifiers have a built-in particle sensor which always monitors the indoor air quality. Sometimes it can give you the wrong data. You need to clean the particle sensors frequently. If you got skeptical about your air purifier, you could bring an air quality monitor to check the indoor air quality independently.

Q. How long an air purifier last?

A. An air purifier lasts 3 to 5 years. Regular maintenance will give you a longer lifespan. Always follow the instructions from the manufacturer to maintain it.

Do you have any questions about air purifiers? Leave your questions in the comment section below.