The site lies on the border of the North Tyneside and Northumberland local authority areas and these along with Blyth Valley Council will decide if the planning application is approved.
A special team has been commissioned from AMEC Earth and Environmental UK to undertake the task over a seven day period.
Specialist sampling equipment will be used to monitor air quality over a 24 hour averaging period with this additional piece of research sitting alongside SITA UKs environmental statement that it is submitting to the three councils.
SITA UK general manager for the north east John Grainger said: Even with the substantial progress that we are now making in increasing recycling and developing new ways of disposing of waste, landfill remains an important part of an integrated waste management solution for Northumberland and North Tyneside, and we simply cannot afford to be without it.
Our research shows that Seghill is the most appropriate site for landfill and this is why we believe that extending Seghill is the best option for Northumberland and North Tyneside.
The monitoring period will be extended if there is adverse weather conditions, with the scope of it agreed to give the authorities all the necessary information available in making their decision.
As part of its extension plans, SITA UK wants to extend the landfills boundaries to cover an area of 19 hectares to the east of the existing site. It also plans to create a landscaping area covering a further 49 hectares which will surround the proposed extension and shield the site from local residential areas.
AMEC senior consultant Liz Hocking said: This monitoring will provide important baseline data that will allow SITA UK and the local councils to have a clear and accurate picture of the air quality around the existing Seghill landfill site.