I agree with what others have said about UV, it should definitely be included; you may also want to include different levels of filtration.

It would likely also be handy to define the type of situation the chart is intended to be used for (e.g., larger scale urban disaster, backcountry use, etc) ... this might also help determine if you should include things like chemical contamination in your chart.

In the past, I've found the following chart helpful:



Source: MEC
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Victory awaits him who has everything in order — luck, people call it. Defeat is certain for him who has neglected to take the necessary precautions in time; this is called bad luck. Roald Amundsen