Noise Exposure Calculator

Under the Control of Noise at Work Regulations 2005 (Reg 4): the lower exposure action value (LEAV) is 80 dB(A) daily exposure, the upper exposure action value (UEAV) is 85 dB(A), and the exposure limit value (ELV) is 87 dB(A). A key distinction (Reg 4(5)): the 80 and 85 dB(A) action values are judged on the noise level WITHOUT hearing protection, but the 87 dB(A) limit is judged at the ear, taking the protection from your hearing protectors into account. This calculator follows that rule — action values on the unprotected LEP,d, the limit on the protected level.

LEP,d is the daily personal noise exposure level, normalised to an 8-hour working day. It accounts for both the noise level and the duration of exposure. A higher noise level for a shorter time can give the same LEP,d as a lower level for longer.

HSE advises assuming the real-world level at the ear is 4 dB higher than the rating predicts, so effective protection is the SNR minus 4 dB (e.g. SNR 30 → 26 dB effective). The 4 dB derate accounts for poor fit, spectacles or other PPE, and inconsistent wear on site. Avoid over-protection too — aim to get the level at the ear below about 85 dB, not far lower, so workers can still hear warnings.

For construction: ear defenders (muffs) with an SNR around 25-30 for high-noise tools, or ear plugs (SNR 20-25) for moderate noise. UK and EU hearing protection to BS EN 352 is marked with an SNR (Single Number Rating); the US NRR is a different scheme. Electronic defenders allow speech while limiting impulse noise. Match the SNR to your noise level and avoid over-protecting.

At 100 dB(A), you reach the 85 dB limit in about 15 minutes. At 105 dB, just 5 minutes. At 110 dB, less than 2 minutes. These follow the 3 dB equal-energy exchange rate used by the Noise Regulations. Most construction power tools need hearing protection for any meaningful period of use.