According to the experts hearing damage is a combination of volume as measured by dB and the amount of time you are exposed to it. If you go by the tables you can stand quite a bit of volume before it being a problem.
From my limited experience those table are, shall we say optimistic. I would take 10 dB's from each of the readings as well as a couple of hours just to make sure. Of course to do so you would need a meter like:
Here is a table for reference. As I stated above take 10 dB's off and two hours just to be safe.
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Duration per day, hours | Sound level dBA slow response
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|
8...........................| 90
6...........................| 92
4...........................| 95
3...........................| 97
2...........................| 100
1 1/2 ......................| 102
1...........................| 105
1/2 ........................| 110
1/4 or less................| 115
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Footnote(1) When the daily noise exposure is composed of two or
more periods of noise exposure of different levels, their combined
effect should be considered, rather than the individual effect of
each. If the sum of the following fractions: C(1)/T(1) + C(2)/T(2)
C(n)/T(n) exceeds unity, then, the mixed exposure should be
considered to exceed the limit value. Cn indicates the total time of
exposure at a specified noise level, and Tn indicates the total time
of exposure permitted at that level. Exposure to impulsive or impact
noise should not exceed 140 dB peak sound pressure level.