or of course it may just be a warning ! As with all these scenarios it is wise not to get into one mindset. Remember your passengers are not all 20 and 30 somethings. Some will be old , young and some in ill health. A number are likely to be hurt in an evacuation. It is not something to be taken lightly.
On the other hand the consequences of delay might be worse in some situations. that is why they pay you big bucks to assimilate all the available information in a given situation and let you make the judgment call.