Firefighters are still at the Mid UK recycling plant near Grantham as 4,000 bales of household waste and shredded carpet continue to smoulder.
Three appliances remain at the scene on Barkston Heath, four days after it began, and are dampening down small pockets of the fire.
Smoke continues to rise and residents living nearby are advised to keep their windows closed.
A Public Health England spokesman said: “Residents in areas affected by the smoke should stay indoors, and keep their doors and windows closed during periods when smoke is affecting their property.
“Motorists who have to travel through the smoke should keep windows closed, turn off air conditioning and keep their air vents closed.
“So far, there have no been reports of any people experiencing ill effects from this fire. The fire and rescue service is on-site dealing with the fire and the other agencies involved will continue to monitor the situation and issue advice to the public, businesses and organisations affected as necessary.
“Any smoke can be an irritant and as such, if people need to be outdoors, they are advised to avoid outside areas affected by any smoke or ash, or to limit the time that they spend in them.
“Some of the substances present in smoke can irritate the lining of the air passages, the skin and the eyes. Respiratory symptoms include coughing and wheezing, breathlessness, sputum (phlegm) production and chest pain. If symptoms occur, people should seek medical advice or call NHS 111.
“Chemicals in the smoke can worsen existing health problems like asthma. People with asthma should carry their inhaler.”
Road surrounding the area are now open.