Radiation: When is it hazardous

See my new phone wallpaper? It's a radiation cipher.

Speaking of radiation, although it's a bit of a superlatively late posting, but for the purposes of my Mom trying to grasp the danger that one might get from the nuclear meltdown in Fukushima Japan, I will, as much as I could, try to post the imminent danger(or its absence) in an utterly layman's term. Help me out on this:

First, there has been no meltdown. The plant was shutdown less than 10% of its full power. This has to be done as far as nuclear safety is concerned because if the heat builds up, it will cause the containment vessels to melt.

Radiation is measured according to Sievert-- a quantitative measure used to determine biological effects of radiation ionizing materials. Reportedly, there were around 3-5 microsieverts of radiation level in the air molecules per hour around the area. That's little higher than normal, but not something that should cause mass hysteria.

Let me give you some comparison as a basis of your health frazzles:

If one flies a lot from Maryland to Detroit to Narita(I use these as example because these are the usual stop overs of my Mom going to the Philippines), he could get a 1,600 microsieverts per year. My Mom isn't flying a lot, so this health risk is only observed from those people in the aviation profession, pilots and flight attendants particularly. Ordinary passengers can get around 30 microsieverts per year, or conversely 5 microsieverts per hour, just the same amount of the radiation level up in Fukushima.

If you are trapped in a bar with smoking bar hoppers, you get around 8,000 microsieverts a year because of the radioactive dust that settled into the tobacco leaves. See the danger of smoking? Smoking gets twice the amount of radiation one gets than those workers in nuclear powerplants.

Everybody gets radiation, from watching TV to your annual X-Rays, even having your dental check up, but these are the radiation levels that are still within safety nets.