We are not all nuclear scientists and with completely conflicting news and opinion on the nuclear situation in Japan you really don’t know what to think. So how can the normal person measure their own radiation exposure and protect against the potential low lying threat of increased radiation exposure?
Please note, these measures are for airborne radiation and not radio active isotopes that have leached into water courses. Whole different threat.
Lets take some easy nto understand information from BBC bitesize:
Photographic film goes darker when it absorbs radiation, just like it does when it absorbs visible light. The more radiation the film absorbs, the darker it is when it is developed.
People who work with radiation wear film badges, which are checked regularly to monitor the levels of radiation absorbed. The diagram shows a typical radiation badge when it is closed and what the inside looks like when it is opened.
A typical radiation badge
There is a light-proof packet of photographic film inside the badge. The more radiation this absorbs, the darker it becomes when it is developed. To get an accurate measure of the dose received, the badge contains different materials that the radiation must penetrate to reach the film. These may include aluminium, copper, lead-tin alloy and plastic. There is also an open area at the centre of the badge.
Notice the ‘light proof’. Creating your own make shift badge is always fraught with inaccuracies and problems. Best is to get yourself a ‘Self-Indicating Instant Radiation Alert Dosimeter (SIRAD)’ which can be around $40
If you are in a tsunami/earthquake devastated zone, do what you can but don’t panic if your film goes cloudy. Accurate results can only be provided by a train medical professional.
Advice on the ground in Japan currently is to cover your mouth with a wet towel and make sure you wash exposed skin areas and clothes to remove any low level excess radiation.