Can My HVAC System Keep My Family Safe from Bacteria and Viruses?

Indoor air always contains some organic contaminants, such as viruses, bacteria, fungi, pollen, and human and animal skin cells. They come into your home every time a door or window is opened, catching a ride on a breeze, clothing, and hair, or shed from people and pets. Fine aerosolized particles of virus and bacteria can stay suspended in the air for minutes or up to several hours when people breathe, cough, or sneeze without covering their mouth and nose. These contaminants can then travel through your home as the HVAC system circulates air. 

Change your HVAC filter

Thanks to the pandemic, people are spending more time than ever inside their homes, making indoor air quality an even bigger concern than it used to be. Managing the air quality in your home starts with something you can do yourself: upgrade your HVAC air filter. The air filter is installed just before the blower cabinet and stops pollutants in the air that flows through the filter when the blower fan is running. A good air filter, replaced regularly, traps most particles before they can get into your HVAC system and recirculate throughout the house.

Check your filter monthly. Whether the filter needs to be changed monthly or quarterly depends on your family–especially if you have pets–and how much dust and pollen are in the air both inside and outside your home. 

The American Society of Heating, Refrigeration and Air Conditioner Engineers (ASHRAE) has developed a rating system for filters called the Minimum Efficiency Reporting Value (MERV). The higher the MERV rating a filter receives, the more particles the filter can trap. Filters for general residential use are rated from MERV 1 up to MERV 16. The average residential HVAC system works well with air filters rated MERV 5 to 8; however, these filters will not trap viruses or bacteria. 

Newer HVAC systems should be able to handle standard filters of higher MERV ratings. At MERV 13, filters will stop almost all particles from entering your air handler, including:

  • • Bacteria and viruses
  • • Pollen and mold spores
  • • Dust and dust mites
  • • Pet dander
  • • Smoke and exhaust fumes
  • • Microplastics

A high-density media air filter is thicker, traps smaller particles, and lasts longer than standard filters. They come in three types:

  • HEPA filter – (MERV of 17 to 20) catches smaller particles than the standard filter but does not work for gas vapors 
  • Activated charcoal/carbon filter – good for homes where smoke and odors are a problem
  • Charged media filter – contains an electrostatic charge to attract smaller particles

These filters stop almost all particles that try to pass through them. However, they may be too thick for your air handler and cause the HVAC system to work harder than normal to pull air through them. Using one of these filters could require modifications of your system to accommodate the increased airflow resistance. Consult an HVAC technician to be sure the upgraded filter you want to use matches your system’s blower capacity.

HVAC UV Lights

Another way to improve your indoor air quality is to install ultraviolet (UV) lights in your HVAC unit or ductwork. UV light has been shown to kill bacteria, viruses, mold, and mildew in hospital settings. Within an HVAC system, UV lights are called ultraviolet germicidal irradiation cleaners (UVGI). 

Photocatalytic oxidation (PCO) cleaners combine UV light with a filter coated in a catalyst (usually titanium dioxide). When the UV light shines on the filter, a chemical reaction occurs that destroys microbes like bacteria, viruses, mold, and fungi caught in the airflow crossing the filter. 

Consult an HVAC technician about the most effective UV lamp size and installation site to address your concerns. To prevent the growth of mold, the light can be placed above the evaporator coil of an indoor air handling unit where it would shine continuously. If your concern is killing airborne pathogens, the best place to install UV lights is in the ductwork; here the lights are coordinated to turn on and off with the blower motor. 

Electronic Air Cleaners

An electronic air cleaner (EAC) uses electricity to create a static charge around its collection plates. As the airflow passes over a pre-filter, large particles are trapped. The smaller contaminants that slip through the pre-filter are charged with electricity and attracted to the collector plates where they get trapped. Bacteria and viruses are destroyed by the electricity running through the plate. EACs only work when the blower motor is running, but unlike media air filters, there is little restriction of airflow that can cause strain on the system. 

Ion generators can be mounted in ductwork to create negative and positive ions which are distributed through the HVAC system when it’s running. Like a magnet, particles are drawn out of the air and attracted to objects in the room with opposite charges, like walls, floors, or furniture. If particles with opposite charges are attracted to each other, they will stick together to become larger and more likely to get trapped in the HVAC filter.

Note that most electronic air cleaners produce ozone, a gas that the U.S. Environmental Protection Agency (EPA) warns is a health hazard. The amount of ozone emitted varies by brand and model. Newly developed ion generators produce very small amounts of ozone that do not exceed public safety standards under normal conditions. Discuss with your HVAC technician which EAC brands are safest for residential use.

If you don’t want to invest in upgrades for your HVAC system for better indoor air quality, at least get your HVAC system professionally cleaned, including blower fans, coils, and ducts. If you don’t have an HVAC maintenance contract, Bower Heating and Air Conditioning is here to help. We are a family-owned business serving the S.W. Virginia area for over 30 years. If you need the services of an HVAC company for repairs, maintenance, or a new installation, please contact us through our website,, or give us a call at (540) 904-7600. 

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