Some color blind users can't detect the difference between orange and red. Color is a useful design extra, but you need to take all users into account.
There are lots of ways to do it. You could just include a page in the manual: "These icons indicate emergencies. Those other icons are just warnings," and expect color-blind users to memorize it. It's not optimal, but it's better than nothing.
Emergency icons might be larger, or perhaps flash (gently). You could include a octagonal stop-sign border around icons that indicate emergencies.
Using color as an additional channel for the 90+% of people in the world who can see it. But the remaining set (over 10% of men) are a sizeable audience.
There are lots of ways to do it. You could just include a page in the manual: "These icons indicate emergencies. Those other icons are just warnings," and expect color-blind users to memorize it. It's not optimal, but it's better than nothing.
Emergency icons might be larger, or perhaps flash (gently). You could include a octagonal stop-sign border around icons that indicate emergencies.
Using color as an additional channel for the 90+% of people in the world who can see it. But the remaining set (over 10% of men) are a sizeable audience.