via iiid.net
In few examples is Design more plainly applied to public service as in public safety communications. And in few instances is clarity and a broad range of users more important for designers to consider.
Use them to do good... or punk'em up on band posters!
Here's a set of American standardized safety icons for download (low resolution is free, high res requires membership) which include:
• General Safety
• Hazard Warnings
• Mandatory Actions
• Prohibited Actions
These are approved by the American National Standards Institute.
Design Credit: Nora Olgyay
Related:
See D.O.T/AIGA wayfinding icon collection for a complementary set of public symbols.