Canadian Blood Services is changing the hours of operation for its' Thunder Bay plasma centre. Spokesperson Michael Hyduk says it was the result of public demand. The clinic hours will be as follows: Monday, Tuesday and Wednesday from Noon until 7:30 pm. Thursday and Friday from 7:30 am until 2 pm. On six select Saturdays 8 am until 11:30 am. Hyduk says the new hours take effect March 29th.