The Carnival cruise ship Ecstasy

MIAMI (CNN) -- The National Transportation Safety Board has sent recommendation letters to cruise vessel operators suggesting they inspect their fleets to reduce the risk of fire.

The letter comes after an investigation of the July fire aboard Carnival Cruise lines Ecstasy vessel.

The recommendation to vessel owners is to inspect immediately ship laundry ventilation systems, including ducts, plenums, and exhaust terminuses for any combustible material, such as lint, and clean the systems to reduce the risk of fire.

They also recommended cruise lines institute a program to check continuously that the vents are clean and do not pose a fire threat.

No one was seriously injured in the Ecstasy fire. There were 2,575 passengers and 920 crew members aboard when a fire broke out near the ship's laundry at the stern of the ship as it was leaving Miami.