Over 40 schools in North and West Yorkshire have been visited by army bomb disposal experts after it was discovered they were storing a potentially hazardous chemical on their premises.

Controlled explosions had to be carried out at the schools - among them some of the region's top independents - and at the University of Hull's science labs after it was realised that many had stocks of dangerous 2.4 dinitrophenylhydrazine (DNPH).

The government's science advisory service advised educational establishments to check whether they had historic supplies of the chemical last autumn, and the last of the explosions took place in December. Some schools faced criticism after they failed to warn nearby residents that army teams would be attending the site.

The chemical can be used safely if stored correctly, but presents a burns hazard if left to dry out. It features on the A Level chemistry syllabus.

Schools which were visited by the Ministry of Defence included:

Batley Grammar School

Scarborough College (independent)

Lightcliffe High School, Halifax

Prince Henry's Grammar School, Otley

All Saints Catholic High School, Huddersfield

City of Leeds School

Trinity Academy, Halifax

Keighley University Academy

Queen Ethelburga's College, York (independent)

Samuel Lister Academy, Bingley

Garforth Academy, Leeds

Mirfield Grammar School

Boston Spa Comprehensive School, Wetherby

St John Fisher Catholic High School, Dewsbury

Hanson School Academy, Bradford

Morley Academy, Leeds

Bruntcliffe High School, Leeds

Parkside School, Bradford

Pudsey Grangefield School, Leeds

Dixons City Academy, Bradford

Appleton Academy, Bradford

Bradford Grammar School (independent)

Allerton Grange School, Leeds

Ryburn Valley School, Sowerby Bridge

Tong High School, Bradford

Goole Academy

John Smeaton High School, Leeds

Bellview Boys School, Bradford

Hemsworth Community College, Pontefract

Oasis Academy, Bradford

Todmorden High School

Hemsworth Community School, Pontefract

Dixon Allerton Academy, Bradford

Ashville College, Harrogate (independent)

Sherburn High School, Elmet

Bootham School, York (independent)

Laisterdyke B & E College, Bradford

Gateways School, Leeds (independent)

Queen Elizabeth Grammar School, Wakefield (independent)

Batley Girls' High School

Carlton Bolling College, Bradford

SOURCE