What are Lex and Pa2h?
The risk of hearing loss depends on the loudness of the noise, and how long the workers are exposed to the noise. Leq is the average noise level measured by an integrating sound level meter. Lex is the Leq that has been corrected for shift lengths other than eight hours. Lex is the noise level, averaged over eight hours, which gives the same noise exposure as would the varying noise over a typical full work shift. Lex, therefore, includes both loudness and length of exposure. Another way of expressing noise exposure is by “noise does”. Noise dose is measured in units called Pascal-squared hours, abbreviated as Pa2h. A noise exposure of 85dBA Lex is equal to 1 Pa2h.
