Does HVAC Purify Air?

According to the Environmental Protection Agency, our indoor air is 2-5 times more polluted than outside air. The indoor air can contain mold, bacteria, viruses, and particles that harm the lungs. In times of the Covid-19 virus, more and more homeowners are wondering how they can keep the air inside their homes clean and whether their HVAC systems are already doing the job.

HVAC units fitted with central air purification systems can purify the air. These purifiers are installed in the ductwork and remove dust, dander, pollen, mold, viruses, and bacteria from the air before the HVAC system circulates it throughout the building. 

Not all HVAC systems can purify indoor air. In this article, I’ll explain how to buy an HVAC air purifier that’s effective and cost-efficient. I’ll also describe a few different types of air filters that you can install in your existing HVAC system to upgrade it and create a healthier living space.

Do HVACs With Pre-Installed Filters Purify Indoor Air?

HVACs with pre-installed air filters don’t purify indoor air because their primary function is to prevent dust from collecting on the unit’s internal components. These mesh filters can trap large-sized airborne particles but can’t capture microscopic organisms that cause diseases.

Large-sized airborne particles like dust can trigger flare-ups in individuals with dust allergies or cause hay fever in vulnerable people. So, an HVAC unit with a pre-installed air filter does clean the air, but only to a small extent

Pollutants like viruses and bacteria have microscopic dimensions and can easily pass through the large pores of the mesh filters that HVAC systems come fitted with. That’s why your HVAC unit needs a specialized air purification system to keep the residents of your house healthy.

Read: How Do I Know If My Air Ducts Need To Be Cleaned?

What Do HVAC Air Purification Systems Purify?

HVAC air purification systems purify indoor air by trapping, killing, or neutralizing dust mites, pet dander, smoke, odors, mold, mildew, disease-causing microorganisms like bacteria and viruses, and volatile organic compounds (VOCs). 

VOCs are gaseous substances. Here are the substances that release VOCs:

  • Paints
  • Lacquers
  • Cleaning supplies
  • Pesticides
  • Furnishings
  • Building materials
  • Graphics and crafts materials like glues, permanent markers, and photographic solutions

Standard office equipment like printers and copiers, carbonless copy paper, and correction fluids also emit VOCs. These gases are harmful to human health when breathed for prolonged periods.

Effective HVAC air purification systems remove airborne particles that have dimensions of 0.1-1 μm (microns). One micron is one-millionth of a meter.

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Here’s what the numbers that indicate the sizes of different airborne particles mean. 

Fine beach sand is about 90 μm in diameter, whereas a strand of human hair is 50-70 μm. Dust, pollen, and mold are less than 10 μm in diameter. Bacteria are usually 1 micron, while viruses are about 0.01 μm in diameter. 

Read: Why Does My Furnace Filter Get Dirty So Quickly

Types of HVAC Air Purifying and Air Filtration Technologies

According to the U.S. Environmental Protection Agency’s Total Exposure Assessment Methodology (TEAM), indoor air in homes in rural and industrialized regions contains 2-5 times more pollutants than outside. What’s more, these pollutants linger in the air long after a person has completed working with the chemicals that released these contaminants. 

An HVAC air purifier is a necessity in homes. 

Not all HVAC air purifiers are created equal. Different models incorporate different purifying and filtration technologies. Read on to find out about the different HVAC air purifying systems before you choose one that suits your space.

HVAC Ultraviolet Light Air Purifier

HVAC ultraviolet (UV) light air purifiers use UV light to kill airborne microorganisms that enter your home. These purifiers are ideal for getting rid of viruses, bacteria, mold, and mildew. They require proper degrees of UV radiation, correct placement of the device, and suitable temperature and humidity levels to work optimally.

Electrostatic Air Purification Systems

HVAC electrostatic air purifiers are powerful and capture airborne particles as tiny as 0.1 microns in size with static electric charges. These air purifiers can block microscopic organisms like viruses from entering your breathing space. 

Carbon Activated Filters

Carbon activated filters for HVAC systems remove smoke, odors, and VOCs (volatile organic compounds) from indoor living and working spaces. 

However, carbon activated filters are gas-phase air filters designed to remove one or more specific gaseous pollutants from the air. For instance, currently available carbon activated filters designed for domestic use can’t remove carbon monoxide produced when wood, charcoal, gas, oil, or kerosene is burned.

HEPA Filters

HEPA (High Energy Particulate Air) filters are commonly used in air filtering and purifying systems. These filters can block airborne particles as tiny in size as .3 microns (μm) from entering your rooms. The powerful filtration technology can block more than 99% of all airborne particles, making your interiors safe for breathing.

Genuine HEPA filters aren’t usually installed in residential HVAC systems. The air handler and the connected ductwork in a typical residential HVAC setup can’t accommodate the physical dimensions of these filters. 

Retrofitting these filters in existing domestic HVAC systems usually requires extensive professional modification of the entire unit. However, specially constructed high-performance homes can have HEPA filters installed in adequately sized and powerful HVAC systems.

Read: Cheap Vs. Expensive Furnace Filters

Choosing an HVAC Air Purifier

After choosing an HVAC air purifier technology for your indoor space, you must ensure you buy an effective and cost-efficient model. Here are some pointers: 

  • Look for the manufacturer’s label to determine how efficient an HVAC air purifier is at removing airborne particles. Manufacturers may indicate the efficiency of a unit at removing particles of a specific size with statements like “removes 99.97% of particles as small as 0.3 μm.”
  • HVAC air purifiers should remove airborne particles with dimensions of 0.1-1 μm to be effective. Choose one that states so on the label.
  • Some manufacturers use the Clean Air Delivery Rate (CADR) measurement system to indicate performance. A higher value indicates greater efficiency.
  • Choose an HVAC air purifier with a high CADR value if you want it to effectively remove smoke (more than pollen or dust) from your indoor space. 
  • Some manufacturers state that they use HEPA filters.
  • Choose an HVAC air purifier that’s appropriately sized for your indoor space. The manufacturer’s label will indicate (in square feet) the size of the area that the purifier will effectively work. 
  • Find a unit that doesn’t intentionally produce ozone during its operation. Ozone is a lung irritant. Examine the manufacturer’s label or visit their website to find out if an HVAC air purifier conforms to the state regulations or industry criteria for ozone generation. 

If you’re retrofitting or upgrading a filter in an existing HVAC system, ensure that you have checked the manufacturer’s guidelines. Not all HVAC units can accommodate higher-efficiency filters. 

Read: Does HVAC Bring In Fresh Air?

Increasing the Efficiency of Your HVAC Air Purifier

An HVAC system with an air purifier is a costly but critical addition to the home. Below are some pointers to help you increase the efficiency of your HVAC air purifier:

  • Follow the manufacturer’s guidelines on cleaning or replacing filters. For instance, clean the filtration plates installed in electrostatic air purifiers after 4-6 weeks of use. You don’t have to replace them. 
  • Ensure that there are no leaks in the ductwork of your HVAC system. 
  • In HVAC systems with UV light air purifiers, ensure that the UV light is connected to the evaporating unit. This activates the UV light only when the HVAC unit is working.
  • In the case of HVAC systems with UV light air purifiers, install the UV light in the air handler. All air entering the HVAC system passes through the air handler.
  • Insulate your home. Ensure there are no cracks, leaks, or crevices through which purified air can escape.

Read: Does HVAC Remove Humidity?


According to the U.S. Environmental Protection Agency, using an HVAC air purifier is one of the most effective ways to keep indoor air clean and safe for breathing. An HVAC system that’s the appropriate size for a building and has a compatible high-efficiency filter promotes healthy living by letting you breathe clean air, free from disease-causing microorganisms and other airborne particles.