Questions to Ask When Choosing a Carbon Air Purifier

What am I trying to remove from the air?

Almost all carbon filter air purifiers also incorporate other filtration techniques, like HEPA filters to remove particles, UV light to anesthetize, and ionizers to convert contaminants into breathable compounds. In all likelihood, these hybrid air filters will provide fresher air, removing other contaminants even if you aren't targeting them.

Which specifications should I pay attention to?

Looking at the stats for a single air purifier can be a puzzling sea of numbers. Unless you have extremely specific needs for your carbon activated air purifier, you probably only need to pay close attention to:

• Room Size: Pay attention to the room dimensions of the carbon air purifier you're considering. It's worth taking the time to measure your walls to make sure you're buying a machine powerful enough for space it will be cleaning.
• Ceilings: Coverage areas for filtration are measured using the standard ceiling height for North America, 8 feet. If your ceilings are higher, make sure to look for air purifier that can handle a coverage area that is proportionately wider than your room.
• Air Flow Rate: Look for a measurement of how many times the purifier can filter the air in a specified sized room each hour. The maximum time turnover rate is 6 times per hour.
• Noise: Since carbon air purifiers use fans to direct air flow through the filter, most models emit some amount of noise. Noisiness can range from completely silent to the sound of a portable fan on the highest setting. To find a quiet air purifier, look at the decibels (dB) of sound. Some air purifiers even have a white noise generator, which are perfect for bedrooms. This feature effectively masks mechanical noises and morphs them into a gentle hum.

Is this carbon air purifier green?

• Replacing Filters: Carbon filters must be replaced once they're saturated with filtered gunk. Filters that can be cleaned and reused are the best choice for minimizing waste. For filters that need to be thrown away and replaced, look for an air purifier that requires replacement less often. Bear in mind that filter turnover as reported by manufacturers is an estimate and will depend on how polluted the air is; the more pollutants in the air, the more often the filter will need to replaced.
• Energy Use: Carbon activated air purifiers run on electricity, so pay attention to how much energy they use relative to each other, wattage or voltage will be listed under the specifications of a product.
• Ozone: Be wary of air purifiers that emit ozone either as a byproduct or as a cleansing medium. Not only is ozone hazardous to breath, ozone contributes to smog and pollution. These types of filters are largely being phased out of mainstream retail outlets, but be wary of machines marketed as air purifiers that are ozone producers by design. Ozone may have a cleansing effect, but why purify the air dangerously when there are more efficient, safe alternatives available?
• Materials and Packaging: Look for air purifiers that are made of materials like metal. Avoid units made with plastic, and look for manufacturers that use recyclable cardboard and don't use Styrofoam.

What is the purpose of activated carbon?

Granular activated carbon is created from familiar items. A hard, carbon based substance, like a coconut husk or hardwood, is burned at extremely high temperatures with steam in a chamber with no oxygen. The end product is activated carbon which is blackened and extremely porous. This process leaves the carbon fibers in a web, which has an enormous surface area. The science behind carbon filtration comes down to two mechanisms:

• Adsorption: molecules in the air adhere to the surface of the carbon
• Catalytic Reduction: the activated carbon has a positive charge which attracts negatively charged ions on contaminants to itself.

What type of carbon filter am I looking for?

With carbon filters, the rule is bigger is better. The larger, deeper, and heavier the filter is, the more activated carbon granules are in it. Each mass of carbon creates surface area for pollutants to latch onto. To be effective for a normal sized room, the carbon filter in your air purifier needs to be more than a couple of pounds to actually improve air quality. Good quality carbon air purifiers have anywhere between 8 and 30 pounds of activated carbon. It's worth purchasing the largest carbon filter your budget allows.

What are my safety concerns?

Luckily, air purifiers aren't inherently dangerous. Like all home appliances, make sure that your home can handle the amount of power needed to operate your air purifier to avoid sparking an electric fire. Additionally, if you have small children or furry-friends, you'll need to take precautions if your purifier is going to be placed in a room that they'll have access to. Choose a model that is sturdy and heavy to avoid knocking it over. Models come in all shapes, so if you have a baby you can look for one with rounded edges.

Do I need extras?

Many air filters come with features that enhance user experience, but don't necessarily affect their air purifying ability. The costs of these extra bells and whistles are tacked onto the price of the model. These special features include:

• Fragrance
• Digital displays
• Remote control
• Filter light change indicator
• White noise creator

These attributes may be something you're willing to spring for, if not, look for a more basic model such as the AllerAir AirTube.