How To Look At A House

McGarry and Madsen's home inspection blog for buyers of  

site-built, mobile/manufactured and modular homes

Will opening the windows reduce the radon level in a house?

Monday, June 25, 2018

Our area is one of several radon hotspots in Florida. Depending on the part of the county you live in, there is a 20% to over 50% chance that the indoor air in your home will be higher than the level at which the Environmental Protection Agency (EPA) recommends hiring a mitigation contractor to fix it.

     When the subject of radon comes up with homebuyers during an inspection, a realtor often chimes in with the comment “All you have to do is open the windows once in a while and you won’t have a radon problem. That’s what I do!”

    Unfortunately, that’s nonsense. While it is possible to reduce the accumulation of radon gas in a home by opening the windows briefly, once the windows, doors, or vents are closed, the radon concentration returns to the previous level in approximately 12 hours according to EPA studies. And, let's face it, nobody really lives with the widows open. We inhabit a closed-up-and-air-conditioned world nowadays.

   Radon is different than other indoor air contaminants like mold, stored paint and chemicals, or formaldehyde gas from new carpets and manufactured wood flooring. They all originate in the home and exhausting indoor air to eliminate them makes sense. But radon rises up into a home from the soil below it when the air pressure inside is less than the pressure in the ground. 

    Homes have a natural upward suction, called the “stack effect,” which is illustrated by the diagram below. Exterior air pressure difference caused by prevailing winds can also create a pressure-differential stack effect.    So most houses naturally pull air from the ground. Opening windows on all sides of the home can equalize pressures between inside and outside, but opening windows on only on one or two sides, or using a exhaust fan, will increase the stack effect.

    Open windows also have disadvantages: increased energy cost to heat the house in winter and cool it in summer, and open windows are a security risk when you are away from home or at night. Although Florida residents love to brag about our balmy sub-tropical weather, most people keep their windows closed and air conditioner on year-round. 

   Natural flow-through ventilation has been proven to be helpful, though, in houses with a basement or crawl space under the floor. Venting those spaces may provide some reduction in the radon concentration in the home above, but the EPA states that “natural ventilation in any type of home should  normally be regarded as only a temporary radon reduction approach.”

    Also see our blog post Can a radon test result be wrong?

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Here’s links to a collection of our blog posts about “RADON":

Can a radon test result be wrong?

What happens to a radon test result if the windows were opened, the test device moved, or there was any other evidence of tampering during the test? 

Where do I find the Florida laws regarding radon?

Can I test vacant land for radon before building a house? 

Is radon mitigation possible for a condominium?

Do radon mitigation systems require maintenance?

What is the average life expectancy of a radon mitigation system?  

Do older houses have higher radon levels than new houses? 

Can the seller tamper with a homebuyer's radon test to change the results?

How long does it take to get the results of a radon test? 

How was it determined that between 15,000 and 22,000 lung cancer deaths each year are caused by radon?

Can a homebuyer do their own radon test for a real estate transaction with a self-test kit?

What is the danger of radon in well water?

What are the symptoms of radon poisoning? 

Does Florida have radon?

Do granite countertops emit radon?

How can I tell if a house has a radon mitigation system? 

Can a mobile/manufactured home have a high radon problem?

Do I need to test for radon when buying a condominium? 

What does a radon mitigation contractor do to lower the radon level in a home?

How can not testing for radon be an expensive mistake for homebuyers? 

Will the radon test come back sky-high in a house that has been empty and closed-up for months? 

What is radon? Should I be concerned about it?

Should I buy a house with a high radon level? 

What is the average radon level of indoor and outdoor air in America?

What is the operating cost of a radon mitigation system? 

• Should I buy a house with a radon mitigation system?

• Does the buyer or seller of a home pay for radon mitigation when the radon test comes back high? 

• What is the probability of having high radon in a Florida house?

• How quickly do I need to reduce a high radon level in my house? 

Does a home inspector check for radon?

What are the problems with underground return air ducts? 

• What is the probability of having high radon in a Florida house?

• What factors can change radon test levels up or down?

    Visit our RADON page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.

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