Seven cars on an 84-car train derailed on or near a swivel-style bridge over Mantua Creek in Paulsboro more than a week ago. A tanker car carrying vinyl chloride, a gas used to make PVC plastic, was ruptured.
The gas led to the evacuation of more than 329 families and businesses.
Air monitors tested 262 homes and 23 businesses Friday and Saturday. Vinyl chloride was not detected.
The evacuation order has been lifted for all but approximately 30 people who live near the derailment site.
The National Transportation Safety Board has left the scene and a preliminary report on the derailment is expected in about two weeks.