'White plume' warning from Salisbury Plain device
Detonating a device found in Chitterne on Salisbury Plain may produce a white plume, residents are being warned.
But the Health Protection Agency said the risk to residents was likely to be very low due to the wind direction and the significant distance from villages.
The incendiary device was unearthed by a contractor at about 16:00 GMT on Tuesday and was made safe after phosphorus was vented overnight.
Police said part of the B390 had been closed for the device to be detonated.