The ratio of the activity of the SLRDs to the activity of the radon gas is called the Equilibration Ratio (ER). Equilibrium usually occurs in about three to four hours. When an individual receives a dose of one WL in 170 hours (a miner's month), the exposure then becomes called a working level month or WLM.
I imagine it was probably my first Prehospital Trauma Life Support class back in 1990 that I first heard of the three collision rule. Since then, it has remained a useful tool in examining the mechanism of injury after auto accidents. If you havenât heard of it, please allow me to elaborate. The three collision rule states that, in any auto accident, there are three collisions that occur and the keen EMT needs to be aware of all three.
If you haven't been in a car accident, consider yourself lucky. Or overdue. By car insurance industry estimates, you will file a claim for a collision about once every 17.9 years. That's if you're an average driver, which, whether you're willing to admit it or not, you likely are.