Despite the weekend explosion that killed six people in Atchison, experts say the nation’s more than 10,000 grain elevators are safer than ever.

The Occupational Safety and Health Administration says an average of 25 grain elevator explosions a year occurred in the late 1970s. That dropped to fewer than nine per year between 2001 and 2005.

Experts say simple rules led to the reduction, such as a ban on welding when grain is being moved, and keeping machines well-oiled to make sure they don’t overheat.