Reference

A 4-gas monitor shows four channels in three different units, and they are not comparable to each other. This guide reads the display field by field: the clean-air baseline, what an oxygen drop implies, why 10% LEL is not 10% gas, what the LOW, HIGH, TWA, STEL and PEAK labels mean, and which hazards the four channels cannot see at all.

Noise exposure is not the loudest reading of the day - it is a time-weighted average of every level a worker meets. This guide shows you how to calculate noise exposure: building an 8-hour TWA, computing dose with OSHA's 90 dBA PEL and 5 dB exchange rate, comparing it to the 85 dBA action level, and where the NIOSH 3 dB rate differs.