The number of Americans who died on the job fell to the lowest level since 1992 last year, dropping 17 per cent to 4,340 across the country in 2009.

Four workers died when scaffolding at this Toronto apartment collapsed on Christmas Eve 2009. (CBC)

The Bureau of Labour Statistics said economic factors played a role in the decrease.

The recession during much of the year caused the total number of hours worked to decline by six per cent in 2009. "And some industries that have historically accounted for a significant share of fatal work injuries, such as construction, experienced even larger declines in employment or hours worked," which could explain the large drop, the agency said in a release.

Fatal work injuries in the construction sector declined by 16 per cent, the agency said. That's a similar decline to the economic activity in the sector overall, as U.S construction spending fell 15 per cent in 2009 to its worst showing on record.

Transportation-related deaths were the most frequent, responsible for 1,682 deaths in 2009, down from 2,130 in 2008.

Canadian data is not yet available, but figures compiled by the Association of Workers Compensation Boards of Canada count 1,036 workplace fatalities in Canada in 2008, just below the 1,055 figure for 2007.

The U.S. report noted that workplace homicides decreased by one per cent in 2009, far less than the 17 per cent average across all subsectors.

Workplace suicides declined 10 per cent from a previous high of 263 cases in 2008 to 237 cases in 2009.

The number of U.S. workplace fatalities declined across all ages and sexes, except for workers under 16, where the death rate increased. Thirty-seven out of 50 states overall reported declining fatalities.