What does an air purifier do and how does it work?


Air purifiers are growing in popularity due to concerns about indoor air quality. The best air purifiers claim to get rid of harmful pollutants and allergens. But can they actually do that? If yes, then how? We answer all your questions.

What is an air purifier?

It is common knowledge that the air outside is polluted with emissions, construction dust, etc. But many people don’t realize that indoor air is also susceptible to contamination from several things, including household cleaners, mold that grows due to excess moisture, building materials, and cigarette smoke. This is where an air purifier comes in.

It is an electrical device that removes pollutants and other fine particles from the ambient air. In doing so, it improves overall indoor air quality.

Most consumer air purifiers are portable and placed in individual rooms to purify their air.

Types of air purifiers

Over the years, several types of air purifiers have made their debut in the market, such as HEPA purifiers, ionizers, ozone generators, UV purifiers and adsorbents. But high-efficiency particulate air (HEPA) air purifiers have become the most popular and recommended option for home use. HEPA air purifiers can also sometimes incorporate features from other types of purifiers to improve their performance. For example, some HEPA purifiers include adsorbents such as activated carbon, ionizers, or UV filters.

Key Components of an Air Purifier

Levoit air purifier
Sees it

A HEPA air purifier is a simple machine. It has three main parts: a housing, a fan and one or more filters.

Housings are usually plastic and have perforations or grilles to allow air to flow in and out of the purification unit. Different manufacturers use different shapes for enclosures. But most often you will find air purifiers with cylindrical or square housings.

A fan is another essential part of any air purifier. It helps the purifier to draw in polluted air and expel filtered air. Air purifiers have different fan speeds to control how fast you want the room air to be filtered. But the faster you run the fan, the more noise it creates.

Finally, filters are the most important part of an air purifier. Some filters can remove particles, while others filter gases better. For example, the HEPA filters used in HEPA purifiers are pleated fiberglass or polypropylene air filters that can theoretically remove almost any particle 0.3 microns or larger. To give you some context, human hair is 17 to 181 microns thick. HEPA filters are great for removing dust, pollen, mold spores, mildew, pet dander, dust mites, soot and many airborne pathogens. They are also useful for filtering cigarette smoke and wildfires, but they cannot remove odors.

On the other hand, an activated carbon filter contains small blocks of carbon which are treated to be highly porous. As a result, it can capture odors and gases like volatile organic compounds (VOCs). VOCs include harmful carcinogens like formaldehyde and benzene.

Besides HEPA and activated carbon filters, some air purifiers also include a pre-filter. It catches larger particles like hair, dust and dirt, which would otherwise clog the HEPA filter. Most pre-filters can be easily cleaned with a vacuum cleaner.

Some air purifiers also include ultraviolet (UV) filters. These filters use UV light to destroy mold spores and other airborne contaminants, including some pathogens. But given the prolonged exposure to UV rays needed to kill contaminants, their effectiveness remains questionable because air can pass through the purifier too quickly.

Remember that most air purifier filters need to be replaced after a certain period of time, usually three to six months, for effective operation.

How does a HEPA purifier work?

Airflow Coway Airmega 300

HEPA purifiers filter ambient air by sucking it in using the built-in fan. This air passes through the various filters present in the machine before being discharged into the room. This is a continuous process, so the air is continuously sucked in, filtered and pumped. Eventually, most of the air flows through the air purifier and the air quality improves dramatically.

But the rate at which most of the air in a room is filtered is different for each air purifier. So, to give you an idea of ​​how long it will take for a particular air purifier to clean the air in your room, the Association of Home Appliance Manufacturers (AAHM) uses a metric called CADR, or Clean Air Delivery Rate. .

How CADR is measured

CADR reflects the volume of filtered air in cubic feet per minute (CFM) delivered by an air purifier. There are different CADR scores for tobacco smoke, pollen and dust.

It is tested at the highest fan speed and with new filters. So if you’re running the air purifier’s fan at a medium setting or if you haven’t replaced the filters in a while, the resulting CADR will be lower than what the manufacturer told you when you purchased the unit. air purifier. Still, it’s a great way to compare air purifiers when shopping and can help you decide which air purifier is best for your room size.

How to choose an air purifier suitable for any room size

The AAHM recommends that the CADR of an air purifier should generally be at least two-thirds of the area of ​​the room. But if you live in an area where wildfires are common, smoke CADR equal to the square footage of the room is best.

Although this seems complicated to calculate, it is actually quite simple. To get the square footage of your room, multiply the length and the width in feet. So if you have a room that is 12 feet long and 10 feet wide, the square footage will be 120 square feet. For this room, the CADR of an ideal air purifier would be at least 80 for each of the values, unless your air purifier also has to deal with wildfire smoke. In this case, you would use an air purifier with at least 120 CADR of smoke.

It is important to remember that the AAHM recommendations assume a ceiling height of eight feet. But if your room’s ceiling is more than eight feet high, it’s a good idea to go for a higher CADR than the recommendation because the purifier will need to purify more air.

Where to put the air purifier?

Air purifier in a living room with incoming and outgoing airflows.

Once you’ve purchased an air purifier, you also need to decide where to place it. The ideal location for an air purifier is usually in the middle of the room. But that’s rarely doable. So, the next best spot would be near a window or door, as the higher air movement at these two spots will help distribute clean air throughout the room. Remember to keep the purifier at least 18 inches from a wall or furniture to avoid blocking airflow.

What about furnace and HVAC filters?

Furnace or HVAC system filters can also remove particulates and improve air quality. But they only work when the furnace or HVAC system is on. You will increase electricity costs if you run them for longer periods of time. But if you still want to use them to filter the air in your home, it’s a good idea to choose a high-efficiency filter with a Minimum Efficiency Ratio Value (MERV) of 13 or higher if your system has it. accepted. MERV represents the ability of a filter to capture particles between 0.3 and 10 microns.

RELATED: How much electricity do all your appliances consume?

Complete ventilation and control of pollutant sources

The best ways to improve indoor air quality are ventilation and the reduction or elimination of sources of pollutants. But air purifiers can effectively supplement ventilation and pollutant source control. So, when shopping for an air purifier, look for ones with HEPA filters and make sure their CADR is sufficient for your room. As a starting point, you can also check out our recommendations for the best air purifiers.

Maria D. Ervin