Health visitor Julie Allen told a family court judge that she had not come across such a "smoky house" in her 10-year career.

She said the child and his father had been surrounded by a "visible cloud of smoke" when she visited, making it difficult for her to breathe.

At the time, the boy had recently had an inhaler prescribed because of breathing problems.

Another social worker described how the child's toys and clothes "smelt heavily of smoke".

Judge Louise Pemberton, who was also told of other concerns about the way the youngster was being cared for, decided he should be placed for adoption.

Details of the case emerged in a written ruling by the judge following a family court hearing in Hull.

The judge said the family could not be identified and she did not identify the local authority which had asked for the boy to be placed for adoption.

But she named individual health and social services staff who had worked with the family.

Judge Pemberton said Ms Allen had "graphically highlighted" concerns about smoke.

The judge said: "On entering the living room Ms Allen described being able to see a visible cloud of smoke surrounding the father and (the boy).

"(The boy) was asleep on the sofa and had been unwell for some time by this point.

"Ms Allen described the room as 'so smoke entrenched that I had difficulty breathing'.

"She immediately expressed concern to the parents as to the impact of such smoke on (the boy), who had already been prescribed an inhaler within the previous month to help his breathing.

"The parents seemed unable both at that stage and when the issue of smoking around (the boy) was raised by any other professional, to acknowledge or appreciate the concern and adapt their behaviour."

Judge Pemberton added: "Ms Allen ... had not come across such a smoky house in many years (she has been a health visitor for 10 years) and never with such a poorly boy sleeping amidst the smoke."