The average amount of space being leased by industrial tenants fell to 22,974 square feet in the first quarter of 2009, its lowest level in 10 years, according a report released by Grubb & Ellis Co. this week.

A number of factors may be influencing the trend, said Robert Bach, the company’s chief economist, adding that the decline is an indication of how the economic crisis is affecting commercial real estate transactions.

Tenants signing new leases may be downsizing their space to a more optimal level following staff reductions or tenants may be taking less space due to a lack in confidence in future expansion. A third reason may be that while smaller, more agile companies are taking advantage of attractive deals in a buyer’s market, larger companies are waiting for an economic rebound.

The size of the average industrial lease in the first quarter was 43 percent smaller than the quarterly average from 2000 through 2008. The average office lease was 50 percent smaller at 12,808 square feet, barely more than its 2008 low point.