It follows the revelation in yesterday's Newcastle Herald by former environment minister Frank Sartor that he tried to introduce the system to the region's mining industry.

He said that although the charge was imposed on about 2000 other sites around NSW, mining companies remained exempt for historical reasons.

"I sought to remove this exemption so that the mining companies had an economic incentive to reduce dust . . . Yet some key people in government vetoed any such action," he wrote.

Mr Sartor was not available to expand on his comments yesterday.

Minerals council deputy chief executive Sue-Ern Tan cited other industrial activities including agriculture, road construction and logging, which were also exempt from load-based licensing.

She argued the system was not always the most appropriate mechanism to reduce pollution.

"Load-based licensing works for point source emissions, where pollutants are emitted through a measurable point like an exhaust pipe," she said.

"But it does not work for emissions that are generated over a large area and cannot be accurately measured."

The Environmental Defenders Office produced a discussion paper last year about the merits of the load-based licensing in the context of pollution produced from electricity generation.

It argued that the system had the potential to ensure the real costs to the environment and public health were factored into the cost of production.

Environmental Defenders Office barrister Kirsty Ruddock said she was surprised that the mining industry was exempt.

"Dust pollution and its affects on communities is an enormous issue that we are exploring in several cases at the moment," she said.