An ERJ-170 flight crew reported strong fumes in the cabin on arrival. They declared an emergency and landed uneventfully.

Narrative

While acting as Captain an emergency was declared due to strong fumes and smoke emanating from the passenger cabin air vents. Approximately fifteen minutes from landing; while in level flight at 12;000 FT; and at an airspeed of 310 KTS; and with the sterile light illuminated; the flight attendants called the flight deck and informed me that there was a very strong odor and some smoke and fumes coming from the vents in the cabin. They further informed me that passengers were beginning to close their gasper vents in order to avoid the fumes. They also reported that the cabin was becoming quite warm. No anomalies were noticed by myself or the First Officer; and no warning or cautions were displayed on the EICAS screen. I advised them to keep me apprised of the situation and ended the communication. Seconds after doing so; an odor; akin to fuel; was smelled by me. The First Officer and I declared an emergency with Approach; and requested to land immediately. We selected to land on XR; as it was the optimal runway relative to our position; and the airport layout. I called the flight attendants to inform them that we had declared an emergency and would be landing immediately. An ACARS message was sent to Dispatch informing them of the situation and our intentions. A normal landing was performed by the First Officer. After stopping the aircraft the First Officer contacted the flight attendants to assess the situation. They informed him that the cabin was clear of any smoke or fumes; and that they believed all of the passengers were okay; therefore we taxied the aircraft to the gate; and the Airport Fire Department began an interior and exterior inspection of the aircraft; and two firefighters were positioned in the jetbridge to assist any passengers who may have been suffering ill effects as a result of the event. A maintenance write-up was made detailing the event; and the Operations Manager was contacted and informed of the details pertaining to the event.