are you asthmatic? You could try an OTC inhaler like Primatene Mist, see if that helps to loosen the tightness in your chest. I get that nagging, hacking cough anytime I breathe with my mouth open in chilled air (I'm asthmatic). I'm still wearing something over my mouth right now in 40 degree temps just to make sure I'm breathing warmed air in. The OTC inhaler might be worth a try.