A Major Incident has been declared on the moors above Manchester, as fire crews battle with a huge grass fire on Saddleworth Moor.
More than 30 homes have been evacuated, and people are being advised to keep doors and windows shut. Those with asthma or other breathing problems should keep their medication with them at all times.
Exhausted firefighters will be helped by 100 soldiers as they battle a moorland blaze which fire chiefs said may last for weeks as the scorching weather continues.
The troops from the 4th Battalion, Royal Regiment of Scotland, will join more than 100 firefighters who have been working rolling 12-hour shifts to tackle the seven square miles of Saddleworth Moor, smouldering with pockets of fire since Sunday.
An RAF Chinook is also on stand-by should Greater Manchester Fire and Rescue Service (GMFRS) request helicopter help to airlift heavy equipment to the high ground.
Mr Hunter said the firefront has widened to two to two-and-a-half miles (3km-4km), in six different locations, and if the wind blows the flames back on to the moors it will act as a "fuel source" for the fire.
Firefighters had been working until dusk on Wednesday night and, as it was too dangerous to go on the moors at night while it is on fire, an assessment at first light showed there was no "significant increase".
Mr Hunter said the soldiers' help would allow the service to keep other fire stations and engines available to deal with emergency calls as the moorland blaze continues
He thanked local residents and businesses who had provided refreshments to officers and asked the public to "be aware" of the smoke and local conditions, keep access routes free for emergency services vehicles and stay away from where they are working.
If the fire worsens, GMFRS will be able to an on-call out an RAF Chinook helicopter, based at RAF Odiham in Hampshire.
It would be used to lift a high-volume pump, capable of pumping 7,000 litres of water a minute, to pump water up on to the moors.
Firefighters have used beaters, and a helicopter has been dropping water on to the fires, which first started on Sunday and led to around 40 homes being evacuated on Tuesday night in Carrbrook, near Stalybridge.
Fire chiefs say it is the worst moorland fire in living memory to hit Saddleworth, a vast tract of barren land, high on the hills straddling Greater Manchester, Yorkshire and Derbyshire.
The impact could even be seen from space as Nasa satellites picked up the plumes of smoke.
Air quality levels in the area are being monitored regularly, with people in affected areas urged to follow advice from Public Health England and keep their windows and doors closed.
A handful of local schools have been closed.
Experts warned that high levels of pollutants generated from the blaze could have a significant effect on people's health.
No rain is forecast for the area for the rest of the week at least.
The cause of the original seat of the fire - thought to be at Buckton Hill, Carrbrook - has not been established but fire chiefs said a detailed investigation would be launched at the appropriate time.
Union says the growing risk represents "another strain on dwindling resources."
The massive moorland fire in Saddleworth is now being investigated as arson.
More than 100 firefighters from Greater Manchester Fire and Rescue Service are continuing to battle against 'unprecedented' moorland fires.