SF340 Captain is informed by the Flight Attendant of a hissing noise as the cabin fills with haze having a strong chemical oder. The cargo smoke light illuminates intermittently and an emergency is declared; with landing at destination airport.

Narrative

While flying at 12;000 ft I noticed a strong chemical-like odor in the cockpit. A few moments later; the flight attendant informed us that S/He heard a pop noise and then a hissing noise as a cloudy haze and odor filled the cabin. As I was speaking to them on the phone; the cargo smoke light on the CWP illuminated. I pulled out the emergency non-normal card and by the time I found the checklist for cargo smoke on the card; the light went out. About 15 seconds later the light re-illuminated and I again reached for the emergency non normal checklist. As it had done previously; the light went out again. At that point; I declared an emergency to air traffic control and they gave us priority handling direct to ZZZ Airport. I informed the flight attendant that we had 5 minutes before landing and informed S/He of a yellow emergency. I also contacted dispatch to let them know we had a strong odor and haze in the cabin; and our cargo smoke light had illuminated. We landed and ARFF was standing by. We turned left; and set the parking brake. ARFF examined the aircraft and said that there was no heat coming from the cargo compartment. We then taxied to the gate and shut down the engines. ARFF further examined the cargo compartment and said that there was no fire. We deplaned the passengers normally through the jet bridge. Soon after landing; I began to experience dizziness and a headache. Upon driving home; I started to feel tightness in my chest. I went to the Medical Center Emergency Room at about XA:30. They checked me in and started me on 100% oxygen for about 45 minutes. At about XB:30; they had a technician come in and draw some blood. Results showed elevated carbon monoxide levels. They kept me on the oxygen until approximately XC:30 when I was discharged with instructions to be re-examined the following day before returning to work.