The Health and Safety Executive (HSE) has issued new guidelines for call centres, to relieve stressful conditions and improve training.
Two million people in Britain now work in call centres, more than the combined number in the coal, steel and motor industries.
The HSE said its research dispelled the view that all call centres were "sweat shops", but said many staff reported their work as very stressful.
Half of those surveyed said their performance was monitored electronically all the time, while team leaders were criticised for raising stress levels by constantly urging staff to answer calls.
Many workers said they found it difficult to cope with abuse from callers. The new guidelines call for staff to be trained to deal with abusive calls.
The HSE also recommended that call handlers be allowed a break of at least five minutes each hour.
Meanwhile, the annual Welsh Call Centre Conference in Cardiff was told that employers should ready themselves to meet tougher regulations from the HSE.
An operations director at safety, health and environmental risk management firm National Britannia, Kelvin Williams, told delegates that air conditioning in offices was very often inadequate for 24 hour working.
"Management should ensure that the office air-conditioning system is adequate to supply fresh clean air for a 24-hours operation, instead of the eight-hours a day most conventional office systems are designed for," Williams said.
He also pointed out the need for staff to take more breaks and the unhealthy practice of staff `hot desking' at workstations that were not adjusted to meet their physical needs.
He added that adequate canteen and recreation facilities for night staff were key requirements for the industry.
"Managers of call centres must ensure that facilities and the working environment provided for night staff are of an equal standard to those that work day-time shifts," he said.
