I fly an unpressurised aircraft for a living, but last week I flew as a pax on a Q400 with the last vestage of a chesty cough, which I had been managing (and flying) with. It may have been just coincidence but that night after flying on the Q400 my chest felt awfull, coughing so much I hardly knew what to do with myself. Does the aircon/pressurisation agravate things? If so, is it a general thing or something particular to that aircraft. A friend who is now an FO but used to be cabin crew on the Bae146 and on the Dash 8 (no prizes for guessing the carrier!) said he never had a problem on the 146 but did on the Dash. (I suggested perhaps it was like a heavy smoker trying to breath cold clear air-the clean air on contaminated lungs being the problem!)