More than 20 schools in Bradford have been forced to close due to smoke pollution from a major blaze involving thousands of tyres.
The fire at a go-kart track on Spring Mill Street in the East Bowling area of the city began early on Monday morning.
At its height, about 100 firefighters were involved in tackling the blaze.
Public health officials have advised residents to only go out if absolutely necessary and keep windows closed due to the risks posed by the fumes.
Bradford Council has published a list of school closures on its website.
Some schools said the acrid smoke from the fire meant they were unable to properly ventilate buildings in compliance with coronavirus regulations.
Pupils were asked to work from home, with schools expected to reopen on Monday.
Bradford Academy's Executive Principle Tehmina Hashmi said they took the decision to close to ensure the safety of pupils after a change in the wind direction on Thursday.
She said the fire had been more visible on Monday, but "yesterday it was very much more the smell".
"I could literally feel my eyes stinging," she added.
Commenting on the risk posed by the smoke, University of Leeds Associate Professor of Atmospheric Composition Dr Jim Mcquaid said burning tyres were renowned "for producing a pretty hideous cocktail of toxic chemicals".
"The smoke from this fire will have an impact on the local communities downwind, especially anyone with underlying respiratory conditions such as asthma," he said.
"What we really need is some heavy rain to damp down this major fire."
Meanwhile, rail services in and out of the nearby Bradford Interchange, which were disrupted by the fire, are expected to resume as normal on Saturday.
Matt Rice, Route Director for Network Rail's North and East route, said: "The amount of smoke in the area brought challenges, but our teams have worked tirelessly to make sure lines can safely reopen."
The city's magistrates' court also closed earlier as a result of drifting smoke.
Some road closures remain in place and more than 40 firefighters are still at the scene.
The Environment Agency said it was helping with the removal of contaminated fire-fighting water, which had collected in pools at the site.
River water quality sampling is also taking place in order to monitor any potential impact from the blaze.
A man aged 59 and a 48-year-old woman were arrested in North Yorkshire on Tuesday in connection with the blaze.
Both have been released on bail, West Yorkshire Police said.