How Are Indoor Air Quality and HVAC Related?

The U.S. Environmental Protection Agency regularly funds research concerning indoor air quality and publishes data, analysis, guidelines and so forth. Based on decades of investigation, the EPA has recognized poor indoor air quality (IAQ) as a serious health risk affecting most Americans. After all, whether at home, in school or on the job, the average American spends 90% of their time indoors. The problem with indoor environments is the potential for dangerously high pollution levels, and this issue has become more prominent as construction science has advanced and homes have become better sealed. Modern homeowners rely on their HVAC systems more than ever to keep their indoor air safe.


The acronym HVAC stands for heating, ventilation and air conditioning. While heating and air conditioning often get the most attention when it comes to home comfort, proper ventilation is essential not only to that coziness but also your health. As mentioned in the introduction, this is particularly true at a time when new homes are sealed tight. That means that with closed doors and windows, very little air gets in or out except through the home ventilation system. If ventilation is inadequate, then pollution levels in the home will continue to rise and undermine your health.

Consider that with all of your windows open, the air in your home would be at the same pollution level as the air outside it. A balance is achieved through natural ventilation. When a home is sealed, you depend on mechanical ventilation to achieve that balance. If ventilation is inadequate, there is a lack of new air, and used air is not exhausted. Indoor air becomes dirtier because existing pollutants linger and new pollutants are introduced not just from outside but from inside the home as well. The EPA recommends actively minimizing the potential indoor pollutant sources along with scheduling an annual inspection of your ventilation to ensure it is current with the latest standards and building codes.


There are many ways people introduce pollutants to their homes, including chemical cleaners, artificial deodorizers and overwatered houseplants. A common way that homeowners inadvertently undermine their home air is with an inefficient furnace or other heating equipment. Consider that many furnaces create carbon as a byproduct of combustion. If the equipment is old or simply not running well, it can lead to high levels of carbon monoxide, which is colorless, odorless, tasteless and highly dangerous when concentrated. Furnaces can also lead to and exacerbate moisture, mildew, mold and pollutant-laden dust, which is why it is so important to have your furnace inspected, tune-up and cleaned each season.

Air Conditioning

There is a natural association between heating and indoor air quality because we often associate heating with burning and airborne particulates. Air conditioning, on the other hand, is often associated with crisp, fresh air. But you should cast any preconceptions aside. Moisture and therefore mildew and mold can be particularly problematic when it comes to air conditioning in a home. Consider that mold spores are present and airborne in your home long before you can detect that mold through smell. As with your heating equipment, it is important to schedule service just prior to heavy usage. Have an AC technician ensure that the system is running well and not causing excess moisture or other issues.


Let us talk about dust for a moment. You may not normally associate dust with your HVAC system, but dust is among the biggest factors in IAQ, and it plays a role in ventilation, heating and air conditioning. Many people think of dust as dirt and perhaps pollen, hair and dead skin. Dust, however, can combine practically any fine particulates. It contains dust mites. It traps pollutants, which is not a good thing since that pollution continues to emit its harmful aspects over time. Dust is a natural part of home life and running an HVAC system. It is imperative that you keep it in check. The EPA recommends dusting and vacuuming with a HEPA filter bag at least once a week and more often if you can.


The U.S. Energy Information Administration estimates that more than 90% of American residences have centralized HVAC systems. Centralized systems involve a duct network throughout the home. This is the skeleton of the ventilation system. The air intake is pushed through these ducts to the various rooms throughout the home. If the furnace or air conditioner is running, then heated or cooled air is pushed through those ducts. Dust will settle in your ducts over time. This is inevitable. If you ever have a mold problem, mold will settle there as well. What this means is that all of your fresh, heated and cooled air will be contaminated by those pollutants as it passes by. This is the reason why the industry recommends having your ducts professionally cleaned every three to five years.

HVAC Filtration

Most centralized HVAC systems will have at least one register—an intake vent. Some homes have two, and some have more than that. These registers have air filters, which are not there to purify your air but rather keep your HVAC system clean. The general rule is to replace them every three months. However, this can vary from home to home. A better approach is to inspect them each month and replace them whenever they are visibly dirty or at the three-month mark.


Achieving good indoor air quality is not limited to proper ventilation and pollution mitigation. Humidity is one of the other factors in play. The rule of thumb for indoor environments is about 30% to 50%. Above 60%, your home is much more prone to mildew and mold. Below 20%, it can be more difficult to breathe, your eyes and skin can become irritated and you become more prone to respiratory illnesses and symptoms. Whether or not the standard residential HVAC system in your home can maintain optimal relative humidity depends on a number of factors. In scenarios where the core system cannot, whole-home humidifiers and whole-home dehumidifiers are an option.

Air Purification

In the ventilation section, it was discussed how in a balanced system the air indoors would have the same pollution as the air outside. If you want the air indoors to be purer, then options include air cleaners and air purification systems. There are both portable room-based and whole-home options, and these systems can range from mechanical filtration to ultraviolet lights that kill bacteria. Be mindful that air purification should be used to control the pollution you could not otherwise control, such as traffic on a busy road. It should not be used to control, for instance, a malfunctioning furnace.

Keeping Your Air Comfortable and Safe

Integrity Heating & Cooling is proud to have served Charlotte, Denver and the neighboring communities for more than 35 years. Our company specializes in the installation, replacement, inspection, maintenance and repair of all manner of heating and air conditioning equipment, and we offer a 100% satisfaction guarantee. Our mission goes beyond ensuring home comfort. We focus on energy efficiency and indoor air quality, and we can perform IAQ testing to determine where your problem areas are.

Contact us today to learn more about these services and to schedule an appointment!

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