More information is required before a reasonable opinion may be offered. Define explosive atmosphere. What is the application? Where are you located and what electrical code you need to comply with?
IEC/EN 60079-0
IEC/EN 60079-7
to name a couple. The suffix will change depending on the spec required but check out the new ATEX guideline 94/9/EG, ATEX 95 as this provides an umbrella Directive to all the standards for motors in hazardous environments.
as a general rule change hastens the laws of unintended consequences. I am retired now but I will relate what happened just after I sold the business [printing related]
the company switched from VOC to water solvent inks and lack of maintenance on the 240V single phase ink pump motor portable cables resulted in one dead by electrocution.
ask your self what is the worst that could happen.