Indoor air pollution is a major concern in urban areas such as Chicago. As a result, air cleaners are no longer just for people with respiratory conditions or other health concerns. While a medium-efficiency furnace filter does a decent job of removing some of the pollutants from the air, there are some contaminants residential filters can't trap. Air cleaners differ from filters in effectiveness.
Air filters vs. Air Cleaners
Every forced-air heating and cooling system is equipped with some type of mechanical filter. These filters are made of dense material that physically, or "mechanically," traps contaminants on the fibers.
The greater the filter material's density, the more efficiently it cleans the air. On the downside, greater density also slows down airflow through the system. This reduced airflow places strain on the blower motor, decreasing its efficiency and increasing wear.
While very dense high-efficiency air filters can trap even the tiniest viruses and smoke particles, they are often not suitable for residential systems. The blower motors in these systems aren't strong enough to maintain sufficient airflow through such a dense filter.
To reach a higher level of air purification, you'll need a method that doesn't depend on a mechanical filter. That's where air cleaners come in.
Some air cleaners do contain mechanical pre-filters to capture larger airborne particles, but their primary purification method is different from that of your furnace filter. Electricity, UV light and activated charcoal filters are among the methods used.
The First Step: Know Your Pollutants
When choosing air purification equipment, it helps to know exactly what types of impurities you want to target. Different types of air cleaners are designed to stop different types of contaminants.
Pollen – The bane of allergy suffers everywhere, pollen can find its way into your home no matter how tightly you seal it or how well you ventilate your home. Medium-efficiency filters can stop most larger pollen particles, but the small fragments still get through. Air cleaners are your best bet for stopping these fragments.
Mold spores – Mold produces tiny reproductive spores that are carried into the air or stick to passing people and animals. This is how mold spores get from the outdoors into your home. Once inside, they can drift into the dark, damp corners of your home and develop into mold, producing more spores right inside your home.
Mold spores aggravate allergies and asthma, as well as increase your risk of respiratory infection. What's more, mold growth damages your home by causing wood, drywall and other structural material to rot.
Combustion particles – If anyone in your home smokes, this will be one of your biggest air quality concerns. In addition, wood-burning, natural gas and other fuel-burning appliances also produce ultrafine particles that can irritate your eyes and respiratory tract, and, with long-term exposure, contribute to cancer. These particles are often too small to be stopped by the average HVAC filter, but the right air cleaner can handle them.
Volatile organic compounds (VOCs) – These airborne chemical fumes come primarily from off-gassing of household material and from cleaning products. Carpets, upholstery and pressed wood are some of the biggest contributors. Long-term exposure may cause organ damage and contribute to cancer. Because these pollutants are in gas form, they slip right through air filters. Removing them requires specialized air cleaning equipment.
Bacteria and viruses – Because these microbes can cause health problems ranging from the common cold to tuberculosis, it's only natural to want them eliminated from your home's air. This goal becomes even more pressing when someone in your household has a severe respiratory condition, such as COPD or a compromised immune system. Many disease-causing pathogens are too small to be captured by a typical residential furnace air filter, but air cleaners can render them harmless.
Dust – Ordinary household dust is primarily lint, but depending on your location and lifestyle, it can also contain fragments of pollen, mold spores, insect parts and other lung irritants. An air cleaner can remove even tiny dust particles from your indoor air.
The Second Step: Choose the Right Type of Air Cleaner
Once you're clear on the types of contaminants you want your new air cleaner to handle, you're next step is to find the models that can do the job.
Electronic air cleaners – Electrical attraction is the method these systems use. A fan in the device draws in your home's air. The air passes through a pre-filter that removes the larger contaminant particles. It then passes through an ionization chamber, where the remaining particles receive an electric charge. The air with the charged particles moves through a series of metal collector plates with an opposite charge. The opposite charges cause the particles to be drawn to the plates and stick there, allowing clean air to flow out into your rooms.
Ultraviolet germicidal irradiation (UVGI) air cleaners – Sufficient exposure to ultraviolet (UV) light breaks apart the genetic material in certain biological contaminants, including mold spores, bacteria and viruses, preventing them from reprodicing. UVGI air purifiers are installed in your HVAC system's ductwork and shine light through the passing air, neutralizing the biological pollutants in the air. If preventing airborne infections is your main goal, a well-designed UVGI system can be a big help. These systems don't target or trap non-organic particles, though, so you'll need a separate filter or cleaner for that.
Photocatalytic oxidation (PCO) air cleaners – These systems shine UV light on a plate coated with titanium oxide. The reactive electrons that occur as a result neutralize both biological contaminants and VOCs. These system are as effective as ozone generators, release only a fraction of the harmful ozone.
Gas phase air cleaners – If you're primarily interested in getting rid of VOCs and odors in your home, this air cleaner is worth considering. A gas phase air cleaner draws air through activated carbon. To be effective, however, the device should contain several pounds of activated carbon. Cheaper models may contain only a few ounces, which isn't enough to improve your indoor air quality. As with UVGI and PCO air cleaners, these devices can't remove particles.
Whole-House vs. Portable Models
The size of your air cleaner is another factor to consider. Air cleaning equipment is available in two basic designs: whole-house (in-duct) and portable (tabletop). Each has its pros and cons, and you may benefit most from using portable air purifiers in addition to a whole-house system. When making your choice, consider that:
- Whole-house models purify all the air in your home as it passes through your heating and cooling system. Portable models can purify only one room at a time.
- Whole-house models are more energy efficient overall. Using a portable model in every room will cost you more than a whole-house air cleaner for the same air cleaning capacity.
- Portable models are easy to move and ideal if you tend to have temporary air quality problems in certain parts of the house. For example, you may want a gas phase air cleaner for a workroom where you use paint or other VOC-producing substances.
- A portable model can support a whole-house system when indoor pollution levels are above average. Consider getting a portable air cleaner for your bedroom if you have trouble with springtime allergies.
Important Questions to Ask During Air Cleaner Selection Process:
The many air purification options available mean there's almost certainly a system that will meet your needs. To make finding the right model easier, make sure you ask a few basic questions about each air cleaning system you're considering.
What will the air cleaner remove? -- Some devices do an excellent job of trapping even the smallest particles, but allow gaseous pollutants right through. Others neutralize bacteria and viruses, but can't stop pollen.
Does the unit have the capacity you require? – To know how effectively an air cleaner will purify the air, you'll first need to calculate the volume of the house or room you need cleaned. Then check the unit's specifications to find out how many air changes per hour (ACH) it can perform for that area. While 0.5 to 1 ACH is sufficient for a whole-house air cleaner, 4 to 6 ACH is preferable for a portable model.
How easy is maintenance? – Look for a model with filters you can easily find in nearby shops. Make sure the system is easy for you to clean and maintain as necessary.
How noisy is the system? – Whole-house models use your furnace blower fan, but portable models contain their own fans. While most are quiet, some make enough noise that it may disturb your sleep.
What are the installation requirements? – Portable models require no installation, but whole-house models must be professionally installed in your HVAC system. Make sure the model you choose is suited to your system and that the installation costs are within your budget.
Even when you know the basics, finding the right air cleaner isn't always a straightforward matter. If you need some professional guidance navigating the world of air quality equipment, contact us at Comfort24-7.com in Chicago, northwest Indiana and southwest Michigan.
Written by Randy Gailit