Telford & Wrekin Council leader Shaun Davies said initial findings from Public Health England regarding the air quality around the fire at Greenway Polymers indicate those living in the area are not at a high risk of harm.
He made his comments in a letter sent to residents near the site of the blaze, which has been burning alongside the M54 since midday on Monday, April 26.
Councillor Davies said there were "still many issues to address and questions to answer" regarding the cause of the fire and the nature of the facility, where £500,000 has been spent to combat the blaze to date.
He said: "We have obtained equipment to monitor air quality, while the Environment Agency has been monitoring the quality of water courses.
"Initially, findings from Public Health England are that the risks to health are low, however because any smoke is an irritant, it is more likely to affect those with existing breathing problems.
"We will continue to monitor both air and water quality and will publish our updates over the coming weeks and months.
"In the meantime, please continue to keep doors and windows shut."
A spokesman for the Environment Agency said: “We are continuing to work with our partners as part of the multi-agency response to the fire at the former waste site in Telford.
“We are also continuing to monitor the watercourses and assess for any adverse impacts, the results of which will be shared with our partners.
“We have provided monitoring equipment to deliver air quality data to our partners at Telford & Wrekin Council and Public Health England.”
Of the £500,000 spent at the site so far, Telford & Wrekin Council has invested £200,000.
"We felt it vital to bring this situation to a close as soon as possible," Councillor Davies said.
"With nobody available to pay to put out the fire and clean up the site, we took the decision to contribute £200,000 to a total estimated investment at this stage of £500,000.
"The money is being used for various activities including demolition of the building, installation of a concrete bund to be filled with water to extinguish the fire and the removal of materials from the site.
"We will make every effort to recover that cost."
An investigation into the cause of the fire is set to get underway.
"Regarding the use of the land, we have rightly been asked why such an operation was allowed on the site," Councillor Davies said.
"The site is privately owned and not under council control or ownership.
"On two occasions we refused planning applications for operations on the site.
"On both occasions, the council's decision were overturned on appeal by government appointed planning inspectors.
"During this fire, meetings have been held with the landowner to discuss the future of the site."
Councillor Davies added: "The severity of the fire was such that it could have taken months to extinguish.
"The reality of the situation is that there is no insurance on the site and the companies that were operating on the site have gone into administration.
"We faced the possibility of several months of air pollution and disruption for residents, businesses, schools and passing traffic on the M54.
"This was something we deemed unacceptable and in the absence of an operator in this situation we felt that we could not allow this situation to continue.
"The alternative was to find a way of putting the fire out quickly."
Councillor Davies said his "personal view" was that "this site should never have been used for this purpose and it should not return to its current purpose".