How Does Ventilation Affect Indoor Air Quality? | Thiele

How Does Ventilation Affect Indoor Air Quality?

How Does Ventilation Affect Indoor Air Quality?

While many homeowners are familiar with HVAC as an acronym for heating and cooling systems, they may overlook the importance of ventilation. Ventilation plays a crucial role in indoor air quality. When you consider some startling facts, you will quickly appreciate how to improve indoor air quality.

First, Americans spend approximately 90 percent of their time indoors. Second, the concentration of volatile organic compounds is 2-5 times higher inside your home.

Your home should be a refuge for you and your family. Promoting and protecting indoor air quality is vital to the comfort and health of your home.

What Is Air Quality?

Air quality assesses the state of air within a specific location. The United States Environmental Protection Agency (EPA) measures the levels of various pollutants and contaminants, including particulate matter, ozone, carbon monoxide, nitrogen dioxide, and sulfur dioxide. For most of us, we think of air pollutants as outdoor concerns within visions of car exhaust, smokestacks and smog.

The EPA has established National Ambient Air Quality Standards (NAAQS) for certain pollutants that are known to be harmful to human health and the environment. These standards apply to both indoor and outdoor sources of pollutants. The information and tools provided by the EPA help individuals understand and improve air quality in their communities.

Outdoor Air Pollution

There are many outdoor air pollutants including particulate matter, ground-level ozone, carbon monoxide, lead, nitrogen dioxide and sulfur dioxide. All of these impact outdoor air quality and are monitored by local and state governments. Because outdoor air flows constantly, many pollutants are dispersed and some are very minimal. For most homeowners, outdoor air is a welcome joy. Fresh air and a steady breeze can be relaxing whereas indoor air can feel stale and dry.

Indoor Air Pollution

Modern building practices do an excellent job of sealing homes from the elements of rain, wind, heat and cold. Ventilation within your indoor air relies on two methods: natural ventilation and mechanical ventilation.

Natural Ventilation Vs Mechanical ventilation

Natural ventilation refers to airflow through openings such as windows, doors and other openings. Natural ventilation can be passive, relying only on natural forces like wind and pressure to drive airflow. Fans, vents and other equipment can also assist in natural ventilation.

The most simple and inexpensive form of improving indoor air quality is to reduce contaminants and irritants by opening windows. An example of this is bathroom and kitchen vent fans. Replacing indoor air with outdoor air can provide adequate indoor air quality in many cases, but extreme outdoor temperatures prevent opening windows and doors.

Mechanical ventilation gives you complete control over air flow and temperatures. The air ducts, vents, air handlers, furnace and air conditioner within your home compose the primary elements of your mechanical ventilation. Mechanical ventilation works in four steps:

  1. Fresh air is drawn into the intake vent.
  2. The air is treated by your HVAC units to the preferred temperature.
  3. Next, a fan and series of ducts distribute fresh air into the home.
  4. Finally, the air is recovered through return ducts and blended with fresh air.

Mechanical ventilation balances pressure within your home without relying on outdoor air and natural ventilation. Outdoor air coming indoors is regulated and filtered. This means outdoor air pollution is largely removed within your home.

When mechanical ventilation is designed and maintained, the primary impacts on indoor air quality are pollutants and humidity.

Indoor Pollutants

Indoor and outdoor air has particulates, but poor air quality within your home is often caused by chemicals, biological growth and exhaust created inside the home.


Dust mites, pet dander, pollen and other allergens build up in your indoor air. While air cleaners filter some of these allergens, standard air filters do not capture many small particulates.


Using gas stoves creates pollution. High levels of moisture, grease, oils and other cooking materials can be released into the air. If not properly ventilated, indoor air pollutants in the HVAC system pose risks including bacterial and mold growth.


High humidity levels in your home and areas within your home become ideal environments for mold and other biological growth. Mold spores and other contaminants can adversely impact the health of sensitive family members especially if allergies and asthma are a concern.

Carbon Monoxide

Many homes now feature carbon monoxide detectors alongside smoke detectors. An odorless, colorless gas, CO sends thousands of people to the hospital every year with symptoms ranging from headaches and dizziness to much more deadly respiratory ailments. Carbon monoxide is a byproduct of burning fossil fuels including natural gas and propane. Furnaces, water heaters and gas stoves are all sources of carbon monoxide.

Volatile Organic Compounds (VOCs)

Common cleaners, personal care products, paints and a variety of other common household items emit chemicals known as VOCs. These gasses can impact your health by causing headaches, dizziness and allergic reactions.

How HVAC Improves Indoor Air Quality

Air movement is the most effective way to reduce pollutants and improve indoor air quality. The team of local HVAC professionals at Thiele Heating and Air Conditioning is extensively trained and highly experienced at designing powerful indoor air quality ventilation systems.

We have several solutions to improve indoor air quality and reduce indoor air pollution:


Designing the best mechanical ventilation system includes heating and cooling units, air handlers, ductwork, vents and return vents. When the out-air ventilation rate is optimized, indoor air pollutants are reduced.

We can build a new system or improve your existing system. Controlling consistent airflow, fixing leaks in ducts and calibrating all equipment, including thermostats, is the first step to better indoor air quality.


Caring for your system is essential to continued performance. Clean equipment, ducts and air filters protect indoor air quality. Our experts are able to consult with you throughout the year by testing the relative humidity and level of indoor air pollutants during annual inspections.

Air Cleaners

Whole house air cleaners are powerful devices for removing air particulates. Whereas most standard air filters are capable of capturing up to 80% of airborne pollutants, whole home air cleaners eliminate as much as 95%. When indoor air pollutants are removed from the air, family members breathe easier, surfaces have less dust and equipment runs smoother.

These devices can be added to most HVAC systems so all air circulating into your air handler is cleaned before flowing through your ducts and into your home.


An extremely common ailment in winter is low relative humidity. As well as feeling colder, dry air impacts the comfort and health of family members. Symptoms of dry air include itchy skin, dry throats, cracked lips, bloody noses and scratchy eyes. A whole house humidifier monitors relative humidity and adds water vapor to the air circulating within your home. Treating your entire home with ideal humidity feels wonderful and has practical benefits to reduce indoor air pollutants. Water vapor in the air holds dust and other particulates in the air. Continuously cycling air pollutants out of your indoor spaces and trapping them in air cleaners provides better respiration within your home.


Like dry air, high humidity impacts indoor air quality. Reducing the level of humidity in sensitive spaces like basements and crawl spaces lowers the risk of mold. A whole house dehumidifier is an effective tool to care for your entire home during humid times of year. Air quality is optimized, and expensive surfaces are protected against excessive moisture levels.

Air Purifiers

One of the latest innovations in indoor air quality is whole house air purifiers. These devices target all the air that carries indoor air pollutants before it enters your air handler. Using ultraviolet light, air purifiers neutralize bacteria, mold, and viruses and remove them from your air. In forced air heating systems and air conditioning designs, air purifiers may provide the strongest defense against allergies, colds and the flu.

How to Test and Improve Indoor Air Quality

No matter what type of furnace and air conditioning system you own, calling on Thiele Heating and Air Conditioning will provide insight into your indoor air pollution. We take the time to listen to your concerns. If you have specific ailments or you simply want to provide a healthier environment for your family, then our HVAC professionals can build an effective solution.