uploaded image

Greetings.
I'm designing a string of logos involving modifications on caution, mandatory and danger signs. I've got some questions:
1) Which font is this (image)?
2) Which fonts are generally used for cauition, danger and mandatory signs such as this:
http://www.onlinesigns.biz/danger_signs.jpg
3) Can I safely and legally use these fonts for my design?
Thanks in advance. God bless you all.

1. difficult to say exactly which font is this. Small sample, very low contrast and heavy jpg distortion. Can be one of several sans serifs.
2. Very legible sans serif fonts. Often specially designed to be very readable on a distance.
3. If you want to be absolutely sure that you are legally using fonts you can
a) buy a commercial font
b) ask the designer of a 'free' font for permission. Almost all 'free' fonts are free for personal/non-profit use. Most of the designers require permission asked for commercial use.

mumble on the side ... Weren't pictograms designed so that the message was clear without text? And if there is text why use a pictogram too?

Well, I'm going to use the modifed pictogram for one of my designs, and also add a new message with that kind of font. I'm going to make a kind of "funny" mandatory sign, so any font used for signs is welcome. I think I'll use Arial because it's free for commercial use.

And yes, if pictograms need text, then they ain't useful, I guess.