BOARDING PAX WHILE ACFT AT ADJOINING GATE DEICING.

Narrative

THE WX THIS DAY WAS SNOWY; FREEZING PRECIPITATION; POOR VISIBILITY AND RWY CONDITIONS AS WELL AS RAMP CONDITIONS. WE (THE CAPT AND I) HAD JUST COME IN FROM A FLT AND SHUTDOWN AND UNLOADED OUR PAX. WE WERE REFUELED AND THE CAPT WENT INSIDE THE TERMINAL TO RECEIVE FLT RELEASE AND WX WHILE I CLEANED UP THE ACFT FOR THE NEXT FLT. I HAD TO USE THE MEN'S ROOM INSIDE THE TERMINAL; SO I WENT UPSTAIRS. WHILE INSIDE; THE GATE AGENTS ANNOUNCED THE BOARDING OF OUR OUTBOUND FLT. I WAS NOT AWARE OR HAD COMMUNICATED TO ANYONE THAT WE WERE READY TO BOARD. THE CAPT MUST BE SUPERVISING THE BOARDING -- I PRESUMED. SO I HURRIED DOWNSTAIRS TO THE RAMP TO THE ACFT. PAX WERE BOARDING WITH THE CAPT AT THE BOTTOM OF THE STAIRS. A DEHAVILLAND DHC-8 WAS BEING DEICED UPWIND IN FRONT OF US. DEICING FLUID MIST WAS TRAVELING DOWNWIND OVER THE PAX OF OUR ACFT AS THEY BOARDED. I HAPPENED TO INHALE SOME OF THIS MIST WHICH SUBSEQUENTLY IRRITATED MY LUNGS. I WAS CONCERNED ABOUT THE SAFETY OF THE PAX AND BELIEVED THEY SHOULD NOT HAVE BEEN BOARDED BY THE RAMP/GATE PEOPLE WHILE THIS DEICING WAS TAKING PLACE AHEAD OF US. THE RAMP PEOPLE ARE NEW AND INEXPERIENCED. I AM CONCERNED ABOUT THE POSSIBLE HEALTH HAZARDS OF INHALING DEICING CHEMICALS AND THE EXPOSURE OF PAX AND FLC MEMBERS TO THIS -- UNNECESSARY DUE TO BAD BOARDING PROCS.