Florida's motorcycle helmet law repeal and fatality rates.

On July 1 2000, the State of Florida exempted adult motorcyclist and moped riders from wearing helmets provided they have medical insurance of 10,000 US dollars. Monthly time series of motorcycle occupant deaths are examined from 1/1994 to 12/2001. The interrupted time series analysis estimates a 48.6% increase in motorcycle occupant deaths the year after the law change. The impact estimate reduces to 38.2% and 21.3% when trends in travel miles and motorcycle registrations are controlled. Our findings suggest that the law's age exemption should be revoked.