Seating at work: ergonomic selection and adjustment

Health and Safety Executive Good practice Seating design Seat (see figure 1(a)) 23 The seat needs to adjust in height to meet the needs of a range of users. The size of the seat needs to be wide enough to seat big people comfortably and deep enough to support the legs of tall people, but not so deep that shorter workers cannot use the backrest. The surface of the seat should not be hollowed or deeply shaped, as this makes it harder to get up or change position. The front edge of the seat needs to be rounded-over and well-padded to prevent it digging into the thighs. Backrest 24 The backrest needs to give firm support to the lower and the middle part of the back. Height adjustment is recommended unless the backrest is high and provides complete support for the back. There should be adequate space for the buttocks; this is usually achieved by leaving a gap between the seat and the backrest. Backrests which tilt with the worker, or whose angle can be adjusted, can improve comfort by providing support for the back in a range of working positions. Armrests 25 For most jobs armrests are not essential. They can restrict arm movement, although for many jobs they can provide comfort. They should be set back from the front edge of the seat, or be adjustable to allow the chair to be drawn up close to the work surface. The height of armrests should not be too low or too high (see figure 1(b)) to cause discomfort. Figure 1(a) Recommended adjustability Figure 1(b) Recommended chair dimensions Seating at work Page 9 of 22