THE A1(M) southbound is closed between Dishforth and Boroughbridge due to a chemical lorry fire.
Emergency services are at the scene of the fire, which was reported just after 4pm.
The fire and rescue service is advising people in nearby Dishforth Airfield to stay indoors with the windows closed for the duration of the night.
The fire involves a lorry parked on the hard shoulder of the south-bound carriage way just past junction 49.
The trailer caught fire and although driver unhitched it and moved the cab away, smoke is blowing on to both roads.
Firefighters from Ripon, Thirsk, Boroughbridge and Harrogate were all sent to the scene.
The A1(M) is closed southbound from Junction 50 to Junction 48, while North Yorkshire Fire and Rescue deal with the blaze.
The Highways Agency is putting in place diversions along the A19 towards York.
Motorists are advised to avoid the area and to remain patient while the emergency services deal with the incident.