I've attached a picture of a chart from a website that you can check out by clicking
here. Anything above 85 dB is dangerous. Not only does the decibel level warrant your attention, so does the exposure time. As you can see below, 8 hours at 85 dB is okay. If you'll also notice, the exposure time decreases drastically. For example, 15 minutes is permissible at 100dB. Running a chain saw for more than 2 minutes without proper hearing protection is very dangerous. Check out
this link for an animated noise level meter. If you only have the time to check out one link, the latter is the best!
