DUST pollution increases almost 13 times as trains pass through suburban areas on their way to the Port of Newcastle.
These were the results of a coal train pollution study of the Lower Hunter conducted over three days in July.
The Australian-first study monitored 165 trains as they passed through Beresfield, Hexham and Mayfield.
Empty trains gave off the most dust.
The Coal Terminal Action Group study used industry-standard equipment.
The results released last week have raised questions on how to keep dust down.
Earlier this month, a Senate inquiry recommended all states and territories have the coal industry introduce covered coal wagons due to concerns of air quality on health.
The NSW Environment Protection Authority also suggested the possibility of spraying coal on trains with a dust suppressant.
However, the NSW Minerals Council dismissed the idea of a suppressant.
It also said the inquiry had failed to give evidence that covering wagons would have any significant effect on dust levels.