A maniac doused a city bus driver and several passengers with what is believed to be pepper spray in Harlem yesterday — the latest in a string of seemingly unprovoked attacks on MTA employees, police said.

The female driver and three passengers were so sickened by the 1:30 p.m. attack at 125th Street and Lexington Avenue that they had to be treated at a hospital.

Police say a Hispanic man walking outside the Bx15 bus approached the vehicle as it was stopped and sprayed the driver through an open window. Six passengers were hit.