Radon originates from Uranium 238, a radioactive element. Almost anywhere in the world you can find some radioactive Uranium 238 in the soil. Radioactive simple means that the element or atom occasionally loses part of itself and changes into a different element. During this radioactive decay the element releases energy and causes varying amounts of damage to whatever surrounds it. The average amount of time it takes before half of the element has decayed or changed is known as the elements half life. Uranium 238 has a 4.5 billion year half life. Half of the uranium 238 is gone because the earth is also about 4.5 billion years old, but there’s still plenty left in the soil. The next element, Thorium 234 has only 24 days before half of it is gone.
The next element after Radium 226 is RADON. Radon is the only noble gas in the final decay chain. Noble gases have no charge (non- reactive) which means radon can freely move through the soil. Radon’s half life is about 4 days, which is just enough time to float through the soil, get into our homes and decay into a series of short lived charged particles that can get lodged in our lungs and damage the lung cells.
Radon floating in the air of our homes decays back into solid particles that are charged (reactive). These short-lived radon decay products can become lodged in our lungs or enter our lungs attached to dust particles. The decay of these solid particles damages our lung tissue and if there is adequate exposure it increases the chances of protracting Lung Cancer.
Reducing the radon levels in a home by sealing cracks or a sump pit has not proven to be very effective. This is partially due to the radon levels in the soil building up to a higher concentration when the openings are sealed so that less soil air comes in but it comes in at a higher radon concentration. Sealing is still a necessary component of sub- slab depressurization radon mitigation systems.
The most common radon system is a sub-slab depressurization system. A fan, located in an attic or outside the building, is used to draw air out from under a basement, crawl space or slab on grade concrete slab. If done properly, the entire area directly below the slab becomes negative in pressure as compared to the air above the slab. This causes the normal airflow out of the soil to reverse and flow into the soil, which effectively stops all infiltration of radon laden soil gas. The sub-slab depressurization system needs to create this sub-slab negative pressure under all slabs that are contributing a significant amount of radon into the building.
A large percentage of the humidity in a basement is from soil gas infiltration. A sub-slab depressurization system stops not only radon but also moist soil gas entry. Customers often report that their de-humidifier in the basement runs less and the basement smells less moldy. A de-humidifier may still be necessary to eliminate other sources of moisture. Jump to Reducing Basement Moisture for lots of additional information.
Electronic radon monitors that give hour by hour radon results can be more accurate than passive test kits such as charcoal detectors or E-Perms. All radon test kits and monitors must pass proficiency tests. Electronic radon monitors offer the advantage of measuring the radon levels every hour, which can indicate unusual radon patterns or possible radon test tampering.
Radon levels are primarily due to three factors, location, location and location. How much radon is in the ground and how easily can gas move through the soil. The type of house and its air tightness is less important.
Some difference is expected because radon levels fluctuate due to weather and house conditions. It is not un-common for radon levels to be twice as high or one half of previous measurements. Upstairs measurements in particular can be significantly different in heating versus cooling seasons. Basement measurements tend to be more consistent in different seasons. A basement measurement that is ten times higher or one tenth of a previous measurement would be unusual.