Air Circulation, Ventilation and Indoor Radon

You've probably passed "Radon 101" this is from the PhD course  

Did you know that all the air in your home is regularly replaced with outside air?  How energy efficient your home is can be measures in air exchanges per hour which could be a few of a lot depending on how well insulated and tight your home is.  

You know that open doors and windows draw air to the opening and out of the house much like an exhaust fan does, the function of one being natural and the other mechanical.  air rushing out of the home creates negative (low) pressure inside your home and since nature abhors a vacuum, radon laden air from the soil around your home rushes in to equalize the pressure.  

If there's something in your air that you don't want to breathe such as smoke from burning broccoli you forgot was steaming on the back burner of the stove, you turn on the exhaust fan which draws the smoke out.  The smoke-filled air leaving the house creates negative air pressure and new air rushes in (air exchange) to compensate: problem solved and everything's back to normal.  

So, will either natural or mechanical ventilation to get radon-laden air out of your house?  NO!  In fact, it will have the opposite effect.  You see, when you create a negative air pressure condition in your house new air must rush in to equalize the pressure.  If all the new air that rushed in was clean outdoor air you might achieve your goal but some of the new air that comes in is from the soil under and around your home right through the foundation and concrete basement floor or first floor slab, which brings in more radon!  Since radon progeny has a relatively short life you exchanged your indoor air with some live progeny and some dead with all new live stuff to breathe into your lungs and cause cancer.  Ventilation is good for removing germ laden air you've exhaled into your home but it doesn't work for radon.

Ventilation is also not good for heating in winter because it draws cold outdoor air in, or cooling in summer because it draws warm outdoor air in.  Circulation on the other hand is good because it moves the conditioned air around moving warm air (which naturally rises) from the ceiling and cool air (which naturally falls) from the floor.  The effect is, the air temperature is moderated so that low things in the room i.e. your feet are the same temperature as high things i.e. your head and you are comfortable all over. 

Ceiling fans are great for circulation.  Did you know good fans have two settings?  In summer you set the fan to blow down onto the floor which pushes the cool air up the walls and around the room.  In winter you set the fan to blow up pushing warm air off the ceiling, down the walls and around the room.  In summer you might set the fan speed on high because moving air has a cooling effect on your skin but in winter you'll want the fan set to the lowest speed because even warm air which is less than body temperature of 98.6 degrees will have a cooling effect.

Good insulation lowers ventilation but in winter keeps heat in and in summer keeps heat out and exhausting air pulls heat out in winter and in summer pulls heat in but in neither case does it clean the air.  The moral of the story is a lot of insulation and some ventilation is good and you should strive for both.  What you probably weren't aware of is good circulation is always good so use your ceiling fans on the proper settings all year long.

How do you control radon?  Pulling the radon out of the soil under and around your house is a good idea as long as you're not pulling it into the house.  Sub-slab ventilation is the common way to do this.  A certified radon mitigation contractor can install a system that draws radon laden out of the soil before it can enter your home and exhausts it through a vent pipe into fresh outdoor air where it is almost immediately diluted and dispersed and quickly dies.

The rate of natural ventilation varies with temperature, wind and weather and of necessity you use mechanical ventilation in the kitchen and bathrooms and as a result radon levels in your home go up and down.  How much; who knows?  A little is okay but too much creates an unhealthy situation.  So make sure you have a digital radon detector in your home.  You can monitor the radon level every day and if the level ever gets too high a siren will sound and call you radon test professional to evaluate the situation and recommend corrective action.                          

The best way to be confident that your radon levels are safe is to install an  electronic radon detector in your home.  You likely already have smoke detectors and carbon monoxide detectors in your home and a radon detector functions in much the same way with one outstanding difference.  A radon detector has a digital display so you can see at any time the radon level in your home displayed in pCi/l, and your radon detector also has a siren to alert you if your indoor radon level exceeds 4 pCi/l.  Smoke detectors and carbon monoxide detectors only alert you when extreme conditions exist but radon detectors give you the confidence of knowing average radon concentrations and whether the are rising or falling.   An electronic radon detector allows you to monitor radon levels in your home every day all year long.

click here now for more information on radon test kits and/or digital monitors from RadonZone.