The reason "shelter in place" is recommended is that it's the smoke that kills. People naturally fear flames but you're more likely to pass out from toxic smoke

The reason "shelter in place" is recommended is that it's the smoke that kills. People naturally fear flames but you're more likely to pass out from toxic smoke and never wake up, without ever seeing actual flame. Several stairwells don't help unless they're completely isolated from each other, which is totally unfeasible.