A person can take approximately 70 decibels as safe for 24 hours.
Normal conversation 45-60 decibels
Air Raid Sirens (140 decibels)
Airplane Taking Off and Thunder (120 decibels)
Garbage Truck (100 decibels)
City Traffic and Truck Driver (90 decibels)
Alarm Clock and Hairdryer (80 decibels)