When the trend of business activity (or otherwise) declines.

 

"If we don't recover from the recent downturn in sales, we will have to lay off some of our employees."

 

"The downturn in travel since the early 2000s directly caused cutbacks in our parts division."

 

"There has been abatement in staffing at our warehouse due to downturns at a major retailer we supply."

 

"Since we specialize in cheap widgets, it looks like the downturn in spending on widgets will mean increases for us."