A dramatic increase in the number of workers engulfed and suffocated in grain bins is prompting OSHA to send letters -- lots of them -- to grain handling facilities, reminding them that they are responsible for complying with the Grain Handling Facility Standard.

The latest batch of 10,000 letters sent by OSHA Assistant Secretary David Michaels is in addition to the more than 3,000 letters OSHA sent to the grain industry in August. OSHA says it's an attempt to reach many more establishments than in the first mailing.

Of the rise in grain bin deaths, a statement from OSHA notes, "According to researchers at Purdue University, there were 51 grain bin entrapments in 2010 -- more than in any year since they started collecting data on entrapments in 1978."

The agency fined two Illinois companies nearly $1.4 million in January after three workers, including two teens (one of them 14 years old), were suffocated in grain bins.