A school bus is stopped near a hazardous-material spill, but no fumes are entering the bus and leaving would expose students to traffic and the spill. What is the best decision-making principle?

1. Evacuate only if staying exposes students to greater risk; sometimes remaining on the bus is safer
2. Always evacuate immediately for any nearby material, regardless of exposure
3. Always send students downwind to inspect the spill first
4. Drive through the spill to reduce delay