E.1 General
The designated fall arrest attachment points on a full body harness are as follows (see 9.1.2.2):
— a rear (dorsal) attachment point, which is arranged to lie centrally between the shoulder blades when the full body harness is worn;
— a front (sternal) attachment point, which is arranged to lie centrally at the bottom of the breastbone when the full body harness is worn.
The advantages and disadvantages of these two attachment points are given in E.2 and E.3. This information is based on HSE document Harness suspension: review and evaluation of existing
information [12].
E.2 Rear attachment point E.2.1 While the user is working E.2.1.1 Advantages
The advantage of a rear attachment point is that the lanyard is out of the way at the back of the user and so will cause minimum interference with the work being carried out.
E.2.1.2 Disadvantages
Disadvantages of a rear attachment point are as follows.
a) It is not possible for the user to see the attachment point and it is difficult to for the user get to the connector to check that it is connected safely to the harness and lanyard.
b) It is more difficult than with a front attachment point for the user to adjust the lanyard to the optimum length, i.e. with no or little slack.
E.2.2 In the event of a fall E.2.2.1 Advantages
A rear attachment point has the following advantages in the event of a feet-first fall.
a) There is minimum backward whiplash effect on the user as the fall is arrested. The user’s head is pushed forward and is stopped by the chin hitting the chest, which is better than it being pushed back so that the neck goes into hyperextension.
b) There is minimum swing.
c) Provided that the harness is correctly adjusted, the lanyard and connector are unlikely to catch the user’s head, either at the front or the back.
E.2.2.2 Disadvantages
A rear attachment point has the following disadvantages. a) There is a large swing in a head-first fall.
b) There is the possibility, in both a feet-first and a head-first fall, of the user hitting the front of their head against the structure.
c) If the harness is not correctly adjusted, the connecting D-ring and connector can pull up during the fall arrest phase and impact forcefully against the back of the user’s head.
d) In a head-first fall, the lanyard and connectors can catch the back of the user’s head.
e) In a head-first fall, depending on the orientation of the user’s body at the time of arrest of the fall, there can be substantial hyperextension of the neck (whiplash).
E.2.3 If the user is held in suspension following a fall E.2.3.1 Advantages
If the user is suspended from a rear attachment point their head is held forwards, which has the advantage that if the user is unconscious they will not swallow their tongue.
E.2.3.2 Disadvantages
A rear attachment point has the following disadvantages.
a) The user’s airway could be blocked by the effect of the effect of the head lolling forward onto the chest. b) The user is held at a steep angle (usually almost vertical). Usually, the geometry of the harness is such that this causes the leg-loops or thigh straps to concentrate pressure on the inside thigh and/or the groin area, which can result in considerable discomfort. It can also cause restriction of the blood vessels in the legs which, together with the steep angle and the user’s lack of ability to move, encourages venous pooling which can lead to the onset of suspension trauma. (A less steep angle of suspension could reduce the potential for these problems to arise.)
c) It is difficult, while the user is in suspension, to attach a foot-loop to the attachment point to aid comfort.
E.2.4 Rescue E.2.4.1 Advantages
Following a fall the user is held at a steep angle (usually almost vertical), which has the following advantages.
a) A vertical rescue from a confined space is easy to carry out. b) A vertical rescue using a winch is easy to carry out.
c) It is easy for a rescuer to carry out the recovery of a casualty in descent.
E.2.4.2 Disadvantages
A rear attachment point has the following disadvantages.
a) It is very difficult for the user to carry out a self-rescue if they are hanging free (i.e. away from the structure) because it is difficult to begin a swing in order to reach the structure.
b) It is difficult, if not impossible, for the user to reach the lanyard in order to attach self-rescue devices.
E.3 Front attachment point E.3.1 While the user is working E.3.1.1 Advantages
Advantages of a front attachment point are as follows.
a) It is easy for the user to adjust the lanyard to the optimum length, i.e. with no or little slack. b) It is easy for the user to check that connections to the harness and the lanyard are correct.
BS 8437:2005
© BSI 29 April 2005 123
E.3.1.2 Disadvantages
A disadvantage of a front attachment point is that the lanyard can sometimes get in the way of the work being carried out.
E.3.2 In the event of a fall E.3.2.1 Advantages
A front attachment point has the following advantages.
a) In a head-first fall, as the fall is arrested the initial movement of the user’s head is likely to be forwards so that the chin hits the chest, thus minimizing any whiplash effect. In the next “bounce” in the fall the head moves backwards but this is less serious as it occurs with less force than the initial movement. b) There is the possibility of the user being able to grab the lanyard at the initiation of a fall, or during the fall, thus reducing rotation of the body and so reducing the likelihood of whiplash.
E.3.2.2 Disadvantages
A front attachment point has the following disadvantages.
a) In a feet-first fall there will always be a head-back swing with the possibility of the user hitting the back of their head against the structure.
b) After a head-back swing there is a powerful swing in the opposite direction, which could cause the user to suffer a frontal impact against the structure.
c) In a feet-first fall there is likely to be some hyperextension of the user’s neck (whiplash).
d) The lanyard and connector could impact forcefully against the front of the user’s head during the fall arrest phase, particularly if the harness has not been adjusted correctly.
E.3.3 If the user is held in suspension following a fall E.3.3.1 Advantages
A front attachment point has the following advantages.
a) Suspension from a front attachment point is usually more comfortable than suspension from a rear attachment point. Usually, the geometry of the harness means that there is less pressure on the inside thigh and/or groin area than with a rear attachment point.
b) It is easy to attach a foot-loop to the attachment point to aid comfort.
E.3.3.2 Disadvantages
A front attachment point has the following disadvantages.
a) If the user is unconscious their head could fall back allowing the tongue to block the airway.
b) Although the angle of suspension is usually less steep than that with a rear attachment point, i.e. the user is suspended in a less vertical position, if the user is injured or unconscious there is still a great risk of suspension trauma. (An even less steep angle of suspension could reduce the potential for this problem to arise.)
E.3.4 Rescue E.3.4.1 Advantages
A front attachment point has the following advantages. a) It is good for self-rescue because:
1) it is easy for the user to start a swing towards the structure;
2) it is easy for the user to attach self-rescue components to the lanyard, e.g. a foot loop or an ascender. b) It is easy for the user to be connected to a rescuer and for the rescuer or a first aider to attend to them. c) It is easy to carry out a snatch (single person) rescue.
E.3.4.2 Disadvantages
A front attachment point has the disadvantage that a vertical rescue from a confined space is less easy than with a rear attachment point because the position in which the user is held is not so close to the vertical.