How loud is that, and is it safe?

Decibels are logarithmic: every 10 dB is ten times the sound energy and roughly twice the perceived loudness.

The level Measured in

Prolonged risk

85 dB — closest reference: damage threshold at 85 dB.

Reference figures are measurements and are rounded; the unit conversion behind them is exact.

Every reference on this page, with its size and its ratio to your number
Reference	Size	Yours ÷ theirs	Note
rustling leaves	20 dB	4.25×
a quiet library	40 dB	2.13×
normal conversation	60 dB	1.42×
a busy street	80 dB	1.06×
damage threshold	85 dB	1×	Over 8 hours
a rock concert	110 dB	0.773×
a jet at 30 m	140 dB	0.607×
a shotgun	165 dB	0.515×

Every 3 dB doubles the sound energy, so the safe exposure time halves: 8 hours at 85 dB becomes 4 at 88 and 15 minutes at 100.
A 10 dB rise sounds about twice as loud but carries ten times the energy. That mismatch is why hearing damage sneaks up on people.

Frequently asked

Above 85 dB damages hearing over an eight-hour exposure, and the safe time halves for every 3 dB. Above 120 dB damage can be immediate.

Because hearing is. The ear handles a trillion-to-one range of intensities, which is unusable on a linear scale.

Levels are A-weighted sound pressure levels at typical distances; the exact figure depends heavily on distance.