If scientists can be believed air quality is getting worse. Those of us paying attention are taking a good hard look at air purifiers, but how do you get the best results from your air purifier?
Many people worldwide suffer from conditions like asthma and allergies and are concerned about air pollution. With more people than ever suffering from conditions like asthma and allergies, many are looking for ways to improve the quality of the air they breathe. Domestic air purifiers are one way to improve air quality inside your house, but there are a few things to consider.
In this article, we’ll discuss making the most of an air purifier, from selection to usage and maintenance. We’ll also answer some common questions, like…
- What is the best type of air purifier for the home?
- How do you know if an air purifier is powerful enough?
- When do I turn on my air purifier?
- Should the windows be open or closed when using an air purifier?
Selecting the Right Air Purifier
The first step to your air quality is selecting the best air purifier for you. This includes choosing the right type of air purification system in the right size for the room. We’ll explain both decisions in more detail.
Types of Air Purifiers
There are several types of domestic air purifiers available, including HEPA filters, air ionizers, ozone generators, and UV filters. Let’s take a closer look at each of these.
The HEPA filter is the most reliable and risk-free type of indoor air purifier. The abbreviation “HEPA” (high-efficiency particulate air) filters meet government-approved efficiency measures. HEPA standards were developed to prevent the spread of radioactive particles released in atomic research and require certified filters to remove 99.97% of particles that are 0.3 microns or larger. For reference, a 0.3-micron particle is only 3% of the smallest size visible to the naked human eye.
True HEPA filters are effective at removing particles, including common allergens like dust, dust mites, pet hair, dander, molds, and pollen from the air. Beware of products labeled “HEPA-like” or “HEPA style,” and only purchase a certified HEPA filter.
Air ionizers (also called “electrostatic precipitators”) are another common type of air purification system. These systems use electricity to charge air particles before discharging them in a small electric field known as a “corona discharge.” This charged field interacts with airborne particles, causing them to cluster together and settle or attracting them to charged metal plates within the purifier. This system removes the particles from the air and makes them easy to clean away.
Overall, air ionizers are effective at removing particles down to 0.01 microns in size (that’s tiny!) and are especially popular among people who live in big cities. They are less effective at removing larger particles and allergens like dust, pollen, dirt, and dander. Air ionizers sometimes emit by-products like ozone and other oxidants, but these tend to be trace amounts below the industrial safety standard of 0.05 ppm.
Ozone generators expose regular oxygen from the air (O2 or dioxygen) to charged particles, causing some oxygen atoms to split and rearrange themselves into ozone (O3). Ozone is unstable and acts as a powerful oxidant. This makes ozone gas very effective at purifying and deodorizing liquids and gases in enclosed spaces, but also makes ozone harmful to organic tissues, including human mucous and respiratory organs.
According to the US Environmental Protection Agency (EPA), ozone levels safe for human exposure are not effective at eliminating contaminants, including odor, viruses, and bacteria. Ozone generators are harmful to health and are not worth the cost.
UV air purifiers are another poor choice for domestic air purification. While UV light at wavelengths of 260 – 270 nanometers is effective at killing bacteria and dust mites on a cellular level, it is not effective in purifying the air. Organisms must be continuously exposed to UV light for sterilization to work, and air purifiers pump air constantly, rendering the UV light ineffective. Furthermore, allergens like dust mites are still irritating once they are dead. Air purifiers using only UV light are not highly effective at improving indoor air quality.
Size and Air Exchanges
The key to filtering contaminants and allergens out of the air in a room is ensuring that all air passes through the filter. The machine must create constant air circulation throughout the room. Most indoor air filters use a motor and a fan to circulate air, which means that many systems make some sound. High-quality models may be much quieter. For best results, all of the air in the room should pass through the filter four to ten times per hour. You can calculate the size of the air purifier you’ll need.
How to Calculate Air Exchanges: Quick Math
There are two typical measurements when selecting the right size.
First, you have square feet. That’s a pretty quick calculation. Multiply the length times the width (l * w)
Let’s say you have a master bedroom that is 15×16 ft (pretty close to average).
15 * 16 = 240 square feet
This Coway AP-1512HH Mighty Air Purifier states it is best for rooms 361 square feet or less. So far so good.
Next, you’ll need to know how fast the air purifier will clean all the air in your room. For this, we find the cubic feet of the room. It’s pretty simple, we just add the height to the previous equation, so now it’s the room’s width, length, and height (width * length * height).
So if our 15X16 foot room has 9-foot ceilings the calculation would look something like this:
15 * 16 * 9 = 2160 cubic feet.
If we look at the Coway AP-1512HH we linked earlier we’ll see it has a 268 CFM.
What does this mean? In our typically sized master bedroom, this air purifier will cycle through all the air in 8 minutes, or just over 7 times an hour.
2160 cubic feet / 268 cfm = 8 minutes
and
60 minutes/ 8 minutes = 7.5 cycles (also known as air exchanges)
That Coway air purifier is well within the range I want an air purifier to be in for our imaginary master bedroom.
Why do we care?
You want your air purifier to run anywhere from 4-10 cycles per hour. Less, and it’s just not effective. More, and you’ve got overkill. I know, bigger is better right? As long as your budget supports it go right ahead. I personally like the right tool for the right job.
Using and Maintaining Air Purifiers
We’ve discussed how to choose the right type of and size of the device for your room. It’s also important to ensure that you place, operate, and maintain the air purifier as directed. Follow the manufacturer’s guidelines, and contact the manufacturer or official retailer with any questions.
Which Room is Best for an Indoor Air Purifier?
The best place for an air purifier is in the room where you spend the most time. The living room may make sense, but think more about the time you spend at home. You actually spend most of your time at home asleep in your bedroom. Most people sleep six to ten hours per day and also spend some waking hours in the bedroom. To get the most benefit from your air purifier, place it in the bedroom.
I’m a fan of running it overnight. My wife always wanted a fan running in the bedroom anyway. Do you wonder how much that would cost? Take a look at our article “Air Purifiers and Energy Bills – Is It Worth It?”
When to Run an Air Purifier
Rooms in your house are not airtight and allow a small amount of air to circulate into and out of the room. An air purifier needs to keep up with the new contaminants entering the room from outside and should remain switched on for the best results.
Windows: Open or Closed
The goal of an indoor air purifier is to keep the “clean” air inside, and the “dirty” air out. Leaving the windows or doors open makes the air purifier less effective because it has to filter the new, dirty air coming in. Keep windows closed while using a domestic air purifier. If you do need to air out the room, turn off the machine before opening windows and doors and turn it on again once you’ve closed the windows and doors.
Air Purifier Cleaning and Maintenance
Air purifiers need different levels of maintenance to work at peak performance. Most domestic HEPA filters last two to four years before they need replacement. Some air ionizers need regular cleaning for the collection panel to remain effective.
Be sure to consider the maintenance required for your air purifier to avoid unexpected costs. Always refer to the manufacturers for maintenance requirements.