Flight Crew Commercial; Flight Crew Instrument
Flight Deck / Cabin / Aircraft Event Illness / Injury; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
General Maintenance Action; General Physical Injury / Incapacitation
Aircraft
During cruise we were at 22;000; we climbed high to avoid moderate icing. We were above the clouds and the temperature had dropped significantly so we began to add more and more heat from the bleed system. As we added heat a noticeable smell began and grew stronger and stronger. After a little while it began to burn our eyes and throat. We discussed the matter and began our descent. I elected to set the pressurization to 10;000 feet to slowly de-pressurize hoping it would draw the smell out of the cabin. This was mildly successful. We landed without further incident and squawked the aircraft. We never had any visual sign of smoke but the smell was acrid enough that we wanted Maintenance to look into the source. The smell resembled a Sharpie marker. No clue [what caused it]; something in the bleed system was aggravated by the heat.
Beech 1900 Captain reported experiencing strong fumes in the cockpit when calling for increased heat at a high altitude.