Exposure limits for air diving operations

Introduction
Exposure limits for air diving operations
Further reading

Introduction

1 This diving information sheet is part of a series of information sheets providing guidance on diving at work. It replaces the following diving safety memorandum: DSM 2/1990. The remaining DSMs have either been replaced by other diving information sheets, or will be cancelled when the Diving at Work Regulations come into force on 1 April 1998.

2 The sheet contains guidance on the maximum time that a diver, using air, should spend under water.

Exposure limits for air diving operations

3 HSE's policy is to recommend that diving, which uses air, should be organised in such a way that the planned bottom times* do not exceed the limits outlined in Table 1.

4 If a nitrox breathing mixture is being used, you can find out the maximum exposure by entering the equivalent air depth of the maximum dive depth in the table below.

Table 1 Maximum bottom time limitation for surface decompression, in-water decompression, and transfer under-pressure decompression diving
Depth		Bottom time limits (minutes)

Metres	Feet	Transfer under-pressure	Surface decompression and in-water decompression

0-12	0-40	240	240
15	50	240	180
18	60	180	120
21	70	180	90
24	80	180	70
27	90	130	60
30	100	110	50
33	110	95	40
36	120	85	35
39	130	75	30
42	140	65	30
45	150	60	25
48	160	55	25
51	170	50	20

* Bottom time:the total elapsed time from when the diver is first exposed to a pressure greater than atmospheric, ie when leaving the surface, or on the start of pressurisation when a closed bell is employed in the observation mode, to the time (next whole minute) that the diver begins decompression (measured in minutes).

Exposure limits for air diving operations

Contents

Introduction

Exposure limits for air diving operations

Further reading