The crew of an A320 with the APU MEL'ed started engines at the gate; turned the bleeds and packs ON and immediately the aircraft filled with a dirty; acrid smell which made some crew members ill and caused the flight to be canceled.

Narrative

Aircraft had one MEL 49-10 inoperative APU. Normal operations with assisted ground air start after starting engine #1 while still at gate; configured aircraft for taxi. Turning both packs on and opening the cross bleed; there was a very noticeable smell and odor. It was a dirty; sharp; acrid; smell in the cockpit. I called the First Flight Attendant; she smelled an odor and said the passengers were complaining about the smell too. I switched off the bleeds and packs and called the gate back to the aircraft. We deplaned all the passengers and I entered a discrepancy in the aircraft log for smell and odor filling out the additional maintenance work sheet. While waiting with the crew for operational decisions to be made. The flight attendants all had complained of headaches and dizziness. The First Officer said he had a headache; I had no symptoms. The flight was canceled and my crew all deadheaded to the crew base. The flight attendants went to the company clinic. Pilots were released and went home.