Saying they have concerns about emissions from the coal burning power plant at Mt. Tom and potential health effects on Holyoke and Northampton, organizers led by the Sierra Club are trying to get the state to impose tougher standards on the plant's operation. "Big coal does make us sick. We are asking that the Mt. Tom plant stop making money by making us sick,'' the Sierra Club's Drew Grande said at a press conference Thursday near the Holyoke YMCA building.