First, Start By Measuring Your Room

Once you choose where your air purifier is going, you’ll want to know the square footage of the space. Every air purifier is designed to cover a certain amount of room’s square footage, so it’s important to make sure the air purifier you choose covers the space you plan to put it in. Instead of guessing at your room size, grab a measuring tape and measure the length and width of the room. Multiply those two numbers to get the area. For example, if your room is 10 feet by 15 feet, the room’s square footage is 150.

• Room Size: 10 x 15 = 150

But just because the air purifier’s box says it covers rooms up to 150 square feet doesn’t mean it’s the right size for your room. That’s because the room’s square footage coverage number on the air purifier box is usually based on ceilings that are eight feet tall. Your home may have ceilings that are taller than eight feet. If that’s the case, then you will have to calculate the cubic footage of the room. Knowing how many cubic feet your room has is important because it determines the total air volume that needs to be cleaned. So, let’s say your 10 x 15 room has 10-foot ceilings. Here’s how to find the cubic footage:

• Room Size: 10 x 15 = 150 square feet
• Cubic Footage: 150 (square footage of room) x 10 (ceiling height) = 1500

So, with the cubic footage above, you’ll need an air purifier that covers at least 1500 square feet. You’ll also want to pay attention to how many times the air purifier cleans that amount of square footage per hour – the more the better. If the box says the machine will cover up to 150 square feet, that generally means it will clean that amount of space on the highest fan speed once an hour. A single room with higher ceilings may require a more powerful one to ensure effective cleaning.

When choosing an air purifier for a single room, look for features like a high-quality HEPA filter, which is essential for removing small particles and improving indoor air quality.

Calculating the Number of Air Purifiers Needed

Determining how many air purifiers you need for your home isn’t a one-size-fits-all answer—it depends on your space, your air quality needs, and your family’s health concerns. The goal is to ensure every area where you spend significant time has access to clean air, whether that means using a single air purifier in a key room or multiple air purifiers throughout your home.

Start with Room Size and Layout:Begin by measuring the square footage and ceiling height of each room to calculate the cubic footage. This helps you match the air purifier capacity to the space. For example, a single air purifier rated for 500 square feet is ideal for a standard bedroom or home office, while a high capacity air purifier can handle larger spaces up to 1,000 square feet. In open concept spaces, such as a combined living room and dining room, you may need a whole home air purifier or more than one high capacity unit to ensure proper air circulation and coverage.

Consider Air Pollution and Health Concerns:If you live near a busy road, experience wildfire smoke, or have high indoor air pollution, you may need more air purifiers to maintain optimal indoor air quality. Households with specific health concerns—like allergies, asthma, or sensitivity to pet dander and dust mites—should prioritize air purification in bedrooms, living rooms, and any personal spaces where you spend the most time.

Account for Air Circulation and Enclosed Spaces:Enclosed rooms, such as bedrooms and home offices, benefit from having a separate air purifier in each space. In multi story homes or areas with poor air circulation, multiple units may be necessary to ensure clean air reaches every corner. For open floor plans, a single high capacity air purifier or strategically placed multiple units can help improve indoor air quality across larger areas.

Step-by-Step Calculation:

1. Measure each room’s square footage and ceiling height to determine cubic feet.
2. Check the Clean Air Delivery Rate (CADR) of the air purifier and ensure it matches or exceeds the room’s size.
3. Assess pollution levels and health needs in each room—add more air purifiers where air quality is a concern.
4. Decide on the number of air purifiers based on your calculations and the specific needs of each space.

Example:For a 1,000-square-foot home with three bedrooms, a living room, and a kitchen:

• Use one high capacity air purifier for the open concept living room and kitchen.
• Place a single air purifier in each bedroom (three total).
• Add an extra unit in areas with high pollution or specific air quality issues, such as a home office or near a source of cooking odors.

Choosing the Right Air Purifier:Look for models with a high CADR rating, HEPA filters for airborne particles, and activated carbon filters to remove volatile organic compounds and odors. Adjustable fan speed and multiple air changes per hour (ACH) allow you to customize air purification based on your needs.

Finding the Balance:While it’s better to have more air purifiers than not enough, having too many air purifiers in a single space can be unnecessary and may not provide extra benefits. Focus on placing the right air purifier in every room where clean air matters most. If you’re unsure, consult an expert or use an online calculator to determine the optimal number of air purifiers for your home.

By carefully considering your home’s layout, air quality, and health needs, you can select the right number of air purifiers to create a healthier, fresher indoor environment for you and your family.

How to Optimize Air Purifier Usage

Air purifiers can be expensive, and they perform an essential function, so you want to make sure it serves you well. It’s important to take good care of the machine and there are some simple steps you can take to keep it performing like it’s supposed to. Always ensure the intake fan is unobstructed to allow for optimal airflow and performance. Regularly maintaining advanced filtration technologies is also crucial for best results.

Filter Replacement

All air purifiers work with a filter and all filters have a lifespan. Some last longer than others, but the general time frame is usually between 6 and 15 months. One of the most important things you can do to extend the life of your air purifier, and ensure you’re breathing clean air, is to replace the filter when it’s recommended.

Whether it’s time to change the filter or not, you should check it at least once a month. Depending on the quality of the air or how hard the purifier has had to work, the filter may get dirtier quicker, and may need changing before the recommended time. If the machine you have contains a permanent filter, make sure you clean it regularly. That will extend the life of the air purifier and the disposable filter.

Clean the Air Purifier

Just like everything else, air purifiers need to be cleaned. Dust the outside of the machine as often as you dust inside your home to make sure there’s no unnecessary build-up. And at least once a month, wipe down the area inside the purifier where the filter goes. It will help keep your machine running longer.

HVAC Filters

Just like the filters for your air purifier, the filters for your HVAC need to be changed regularly. These filters help protect the sensitive components of your HVAC system, while also filtering out large particles like dirt, dust and hair.

HVAC filters should be changed, on average, every three months. If you have pets in your home, you should change the filter every two months. If you have more than one pet or suffer from allergies or respiratory problems, you should change the filter once a month.

Air Purifier Placement

You may not realize that where you put your air purifier is just as important as how often you run it. Where the machine sits can affect how well it performs. If the air purifier is in your bedroom, place it near your “breathing zone.” Typically, placing it on a nightstand or near the head of the bed will be most effective. Each enclosed space in your home may require its own air purifier, since limited air exchange between enclosed spaces means a single unit cannot effectively clean the air in multiple rooms.

If the air purifier is in the living room, it’s best to place it off the ground and near places with the highest air flow—think doorways, near windows, and along walls. Don’t ever put your air purifier directly behind a curtain or piece of furniture. That will obstruct the machine and keep it from performing correctly.

Air Quality Monitoring

More and more air purifiers are coming equipped with air quality monitors. These machines will track air quality in real time and adjust the fan speed accordingly. But if your air purifier doesn’t have one, it may be worth investing in an air quality monitor. That way you can know when to turn the fan speed of the purifier up to clean the air.

When to Replace Your Home Air Filters

As mentioned, it’s important to replace the filters in your air purifier regularly to keep the machine working correctly and to make sure the air inside your home is as clean as it can be. But there are several factors that can result in the need to replace the filters more often than the recommendation on the box. The presence of airborne irritants and air pollutants, such as dust, pet dander, and chemical particles, can increase the frequency of filter maintenance to ensure effective removal and maintain indoor air quality.

For instance, if you or someone you live with has pollen allergies, you will want to change the filters more often during pollen season. This is especially true if you like to open the windows on warm, spring days.

If there is a smoker in the house, you’ll want to change your filters more often. According to the CDC, tobacco smoke has been proven to be a health hazard. Because of the way it sticks to other particles in the air, it has the tendency to linger much longer. For those reasons, it can dirty up filters quicker than other pollutants and create the need for them to be changed more often.

Some air purifiers contain activated carbon filters. They’re highly effective at removing odors, gasses and VOCs from the air by adsorbing them into the porous material. Because of the process, these filters have to be changed out about every three months.

What Factors Affect Filtered Air Quality?

If you’ve done any research on , you’ve likely heard of ionization. Some machines are equipped with ionizers which use negative ions to remove small particles from the air. Ionizers will help mask the smell of odors in your home and make the air seem fresher.

The California Air Resources Board has established that the problem with ionizers is they can also emit ozone, which is an unhealthy lung irritant. According to the EPA, inhaling small amounts of ozone can cause an immediate reaction including chest pain, coughing, difficulty breathing, shortness of breath, and throat irritation. Individuals with respiratory conditions are especially vulnerable to these effects, as ozone exposure can further aggravate asthma, allergies, and other respiratory issues. Over time, breathing in ozone can make asthma worse, give you a higher risk of respiratory infections, reduce your lung function, and cause lung inflammation. It’s a good rule of thumb to stay away from air purifiers with ionizers, or turn the ionizer off if the machine has that option.

Are Air Purifiers Good for the Environment?

Even if you don’t have an air purifier for each room, having one in use is a great addition to help clean the indoor air. We don’t truly realize all the irritants that can be floating around in our homes on any given day. Whether it’s dust, allergens, or gasses and VOCs, an air purifier can pull those things out of the air, trap them in the filter, and send fresher, purer, more breathable air back out, resulting in cleaner, fresh air throughout your home. Eliminating those things is good for the environment because if left alone, they can lead to chronic health issues.

The units run on electricity, but most companies make them energy efficient so you’ll see very little difference in your electric bill. The air purifiers and filters themselves aren’t recyclable. They may eventually end up in a landfill, which can be an environmental mark against them. As Dr. Richard Corsi, Dean of the College of Engineering at Portland State University details, “While air purifiers improve indoor air quality, they also have an environmental footprint. Energy-efficient models and proper filter disposal can mitigate some of the negative impacts.” So, if properly used and disposed of, air purifiers are generally made to last and don’t have to be frequently tossed out and replaced, and can be argued that the environmental benefits outweigh the risks.

What is an Energy Star Rating?

The Energy Star rating is a certification given by the U.S. Environmental Protection Agency (EPA) to products that meet certain energy efficiency guidelines. Products with this rating are designed to consume less energy, reduce greenhouse gas emissions, and lower utility bills, all while maintaining high performance standards. For air purifiers, an Energy Star rated model will use less electricity than non-rated models, making it a more environmentally friendly choice while still being effective.

Final Thought

Whether you need one or multiple units depends on multiple factors such as if you suffer from allergies, the time of year it is, the size of your home, and how polluted your air is. For larger spaces, you may need to consider adding a second air purifier to ensure full coverage. To effectively pick the right number of air purifiers for your needs, be sure to understand how to determine room size, the different filter types, replacement needs, and where to properly place the devices. Using separate air purifiers for different rooms or specific needs can help optimize air quality throughout your home.

When deciding on placement, remember that one purifier may not be sufficient for multiple rooms, especially if there are barriers or closed doors. In some cases, one unit can handle a small or open-concept space, but larger homes or homes with multiple rooms will benefit from additional units.

In summary, one purifier or one unit may be enough for a small home or studio, but larger homes with multiple rooms will require more air purifiers to ensure comprehensive air cleaning.

References

• U.S. Environmental Protection Agency. The Inside Story: A Guide to Indoor Air Quality. EPA website. Accessed July 9, 2024. https://www.epa.gov/indoor-air-quality-iaq/inside-story-guide-indoor-air-quality