Modeling the impact of the components of long work hours on injuries and "accidents"

Many of the industrial disasters of the last few decades, including Three Mile island, Chernobyl, Bhopal, Exxon Valdez, and the Estonia ferry, have occurred in the early hours of the morning. Follow-up investigations concluded that they were at least partially attributable to human fatigue and/or error. The potential impact of long work hours on health and safety is a major concern that has resulted in various work hour regulations.

The risk of injuries and "accidents" (incidents) associated with features of work schedules from published epidemiological studies are pooled using an additive model to form a "Risk Index." The estimated risks of an incident for various standard work schedules are presented using the proposed model.

The estimated risk of an injury or accident associated with any given number of weekly work hours varies substantially depending on how work hours are comprised. The risk depends on the length and type of shift, as well as the frequency of rest breaks.

We conclude that placing a limit on the risk associated with a particular work schedule is likely more effective than setting daily, weekly or monthly work hour regulations in keeping workplace safety within acceptable limits.