Following three catastrophic dust explosions that killed 14 workers in 2003, the US Chemical Safety and Hazard Investigation Board (CSB) initiated a study of dust explosions in general industry and what can be done to reduce their risk. The CSB has concluded that combustible dust explosions are a serious hazard in American industry.

The CSB report reminds us that dust explosions can either be primary or secondary, and that a secondary explosion occurs when dust accumulated on floors or other surfaces is lofted and ignited by a primary explosion

The best way to prevent secondary dust explosions is to minimize dust accumulations. Ensuring good housekeeping can effectively prevent secondary dust explosions. However, proper equipment and techniques to clean combustible dust accumulations must be used. Care
must be taken to minimize dust clouds, and only vacuum cleaners approved for combustible dust locations used as mentioned in NFPA 654 (2013) 8.2.3.2

You can read the complete report at:
http://www.csb.gov/assets/1/19/dust_final_report_website_11-17-06.pdf