The office has agreed to take up the case of hundreds of residents who have been lobbying for decades for a public health study into the effects of the region's two largest industries.

Scientific environmental and medical research is being used to prepare a submission to the Government.

Accounts of local doctors who have recorded increasing incidences of respiratory illnesses in the region during recent years will also be referred to in the submission.

"We will be putting the ministers for health, planning and environment on notice that this is an issue that needs to be properly investigated as a matter of urgency," Environmental Defender's Office principal solicitor Kirsty Ruddock said.

"We are calling on them to satisfy their duty of care by doing a proper population health study in the region."

If it was proved in years to come the Government failed in its duty of care, it could potentially face a class action from those who had contracted air pollution-related illnesses while living and working in the Upper Hunter.

It is believed the case is one of the first of its kind.

"It's a fairly unusual case for us to take on," Ms Ruddock said.

"A lot of the issues that come to our attention relate to specific pollutants but this is more of a general air quality issue.

"We are doing this because we believe these communities need to be represented."

Health authorities have been reluctant to carry out a public health study of the Upper Hunter because they believe the area does not have an adequate population base to make such a study scientifically valid.

MineWatch president and Camberwell resident Wendy Bowman said she approached the Environmental Defenders Office as a last resort.

"We are not going to go away there are so many people who have become sick as a result of the air," she said.

The Environmental Defenders Office is expected to present its submission to the Government in the next six weeks.