Straight Talk Articles

Breathe Easy About Your Home’s Air Quality
November, 2020

Dear Pat and Brad: 

I read your column a few months back about sealing air leaks, but I’ve heard a home that’s too tight can be unhealthy. How can I be sure I have healthy air as I seal up leaks? – Lee


Dear Lee:

Sealing air leaks is one of the best ways to make your home more energy-efficient, and you can take steps to be sure your home has an adequate amount of healthy fresh air.


The average home loses about half its air volume every hour, so it can be tightened up considerably, often at low cost, and still have more than enough healthy fresh air.

Pollutants are the cause of poor indoor air quality, and most deadly pollutant is carbon monoxide (CO).  It can come from furnaces, water heaters or stoves that burn natural gas, propane or wood.  The problem usually occurs in devices that are old, in need of repair or installed or operated in a manner that prevents clear and unobstructed supply and exhaust of combustion air.  Excessive moisture in the air should be considered as an indoor pollutant, because mold and dust mites thrive in when relative humidity is above 60%(1). Some areas of the country have radon, a radioactive, cancer-causing gas that can seep into your basement. Volatile Organic Compounds (VOCs) can be a health problem, and they are in a wide variety of home products, such as paint, particle board and carpet.  And tobacco smoke, one of the worst causes of cancer, needs a way to escape – or better yet, smoke outside.


One sign your house is too tight is condensation on the windows,(2), which can happen if moist air doesn’t exit the home at an adequate rate.  Other pollutants trapped in a home that’s too tight can cause physical reactions such as coughing or sneezing. Carbon monoxide causes more severe reactions such as headaches, dizziness, nausea or vomiting, shortness of breath, confusion, blurred vision or loss of consciousness.(3) 


What can you do to ensure healthy indoor air as you become more energy efficient?  The first strategy, according to the Environmental Protection Agency (EPA), is to eliminate or reduce the source of pollution.(4)  And the first pollutant to eliminate is carbon monoxide.  If you have a combustion furnace it should be inspected and tuned up regularly by a professional.  If you have any combustion appliances it is critical that CO detectors are installed and replaced every 5 to 7 years.(5)   


If you live in an area with radon, which you can determine by checking out EPA’s radon map,(6)  keep it out of your home because it is the second leading cause of lung cancer.(7)  Radon tests are not expensive, and your local health authorities or your electric co-op will know how you can get one done. If radon levels are too high, you’ll need to hire a professional to install a system that will divert radon gas to the outside.


Other pollutant reduction measures include:

  • No smoking inside

  • Run the exhaust fans in bathrooms and your kitchen after use

  • Store toxic cleaning and painting products outside

  • Never idle a vehicle, even for a minute, in an attached garage


The second strategy is ventilation.Your home probably has more than enough natural ventilation from outside air leaking into the home.If you suspect this isn’t adequate, the best way to know for sure is to hire an energy auditor to do a blower door test.Some auditors and inspectors can do a healthy home inspection.


Many experts recommend sealing the home as tight as possible and using mechanical ventilation to ensure a consistent and adequate supply of outside air.The most energy efficient ventilation system is a heat recovery ventilator (HRV),(8), which pulls in fresh air from outside and captures the heat from indoor air before it is exhausted to the outside.


The third and final strategy is to clean the air. The easiest step is to simply change your furnace filter at least once every three months, and keep your furnace supply and return air registers free of obstructions.  If any rooms do not have an air return, keep the doors open.  There are a wide variety of home air cleaning systems available, some are effective and some are not.  EPA has a guide available at


We hope these steps will give you confidence to seal up your home safely.

This column was co-written by Pat Keegan and Brad Thiessen of Collaborative Efficiency. For more information on over-sealing your home, go to the November 2020 More Information Page.



(2) fixing basement moisture problems is a major topic all its own, with a variety of approaches.


(4) For more info, see our August 2020 article on Sealing Air Leaks.






Condensation on your windows could be a sign your home is sealed too tight: Source: Rene Enhnardt,