Schools in Kent have been urged by education officials to prepare for possible lockdown if levels of air pollution rise because of more traffic congestion after Brexit.

The advice is contained in a six page document by Kent County Council to schools, outlining what they should do to prepare for possible disruption when the Brexit deadline passes in March.

Under a section headed “Potential challenges to schools and communities” schools are advised to “consider planning for possible lockdown if air quality deteriorates.”

It goes on to say they should “consider road safety with the increased traffic and impatience of drivers.”

The guidance offered in the briefing note also warns there is the possibility of an increased number of unaccompanied asylum seeking children and migrants arriving in Kent.

It warns Brexit could see more migrants arriving in Kent “as a consequence of the increased opportunity afforded by congestion on the continent.”

Headteachers are also advised to “be mindful of possible disruption” caused by pupil absences and “even the delivery of examination results.”

KCC says headteachers may need to consider closing completely or partially in the event of staff being unable to travel.

But it recommends sites limit the likelihood of closing by encouraging staff to find alternative ways of getting to work - including walking or cycling.

It suggests schools may be hit by logistical delays “causing possible supply-side disruption resulting in changes in maintaining service delivery including fuel food medicines and contractors.”

The guidance says the impact of Brexit on Kent is likely to be greater than elsewhere and “disruption could continue for up to several months.”

Locations near the M20 and M2 and A2 could be affected more than others and the initial impact would be restricted to “staff and pupil delays.”

One headteacher said schools would use common sense to respond to any disruption but it would be difficult to deal with staff shortages.

Paul Luxmoore, chief executive of the Coastal Academies Trust, which runs five academies in east Kent, said: “We have quite a large number of staff who live outside Thanet - such as Canterbury - and journeys to school might well be disrupted. How we are supposed to plan for this, God knows. We’ll deal with it if it happens.”

In December the council published a 17-page report on the challenges a “no deal” Brexit could result in.

It warned: “An inability to travel around the county may have a direct impact on KCC’s delivery of statutory services.”

Recent figures released by the council show that the number of child asylum seekers arriving in Kent has declined significantly, falling to 171, the lowest figure for five years.

Cllr Trudy Dean, opposition Liberal Democrat spokesman, said: "I think some of the recommendations on the challenges schools and teachers face are self-evident."

"It could be like a snow emergency but over an extended time that lasts for several months. Some of the issues do seem remote but there are real ones around transport, delivery of fuel and school meals. I imagine the number of schools that will be affected by air quality will be relatively small."

She said it was too early to consider cancelling school trips as "no-one knows what the reaction will be."

KCC has been approached to comment.