Back in the early 1980s, when I was reporter and presenter on TV Eye - a nationally networked UK current affairs programme - I was sent to Portugal to investigate a series of mysterious deaths of British holidaymakers in Portuguese resorts.
The deaths had all occurred over the space of a couple of months and all involved holidaymakers, often golfers, who had escaped the British winter for some Portuguese sunshine.
Accommodation for the summer trade was often empty during the winter; chalets were often built alongside golf courses and British golfers were a welcome boost to trade. The tourist operators, though, as well as the Portuguese and British authorities, became increasingly concerned at the unexplained deaths.
The deaths all had common features. They usually occurred in the early evening, often after a round of golf. The victims typically exhibited no symptoms prior to collapsing for apparently no reason and dying within a few minutes.
One typical case was that of a middle-aged British couple who had returned to their accommodation after a round of golf. As the sun went down and the temperature dropped, they had closed the windows and the wife had apparently gone to run a bath. She was discovered naked lying beside her husband on the living-room floor; it seemed that they had died within a minute or two of each other.
The Portuguese doctors were totally flummoxed by these deaths. The only symptom common to all the deaths was the victims all had a rosy colour, perhaps because of the sunshine they had enjoyed. The death certificates variously ascribed the deaths to sun stroke, food poisoning and, in the case of the golfing couple and reflecting the wife's nakedness, to "excessive love-making".
The British media were equally mystified. The finger was pointed at lax Portuguese building standards and it was speculated that gas leaks were responsible. The Portuguese authorities were adamant, however, that there was no sign of the gas supply being defective in any way, nor were the symptoms consistent with gas poisoning.
By the time I arrived with a film crew, the tourist trade for winter golfers had come to a premature halt. I began my inquiries when most possibilities had been dismissed.
I could place no reliance on the Portuguese death certificates. They were so much at variance with each other and in some cases so fanciful that they were completely unhelpful. The state of Portuguese medicine at the time was illustrated by my discovery of organs taken from one victim during an autopsy stored in an empty Nescafe tin in a shed!
It was clear to me, however, that the victims had died from some kind of traumatic cessation of their ability to breathe properly. I was eventually able, following considerable research of medical histories and of meteorological records for those couple of months, to establish what had happened.
All the cases seemed to involve the use of some form of heating - sometimes just to warm the room or to heat water for a bath or shower. On the date of each death, the external temperature had dropped suddenly and an inversion of usual temperature layers had occurred; colder air had dropped suddenly closer to ground level.
The holiday-makers closed windows that would normally have remained open in summer; the heaters had all been properly flued, but the flues were not high or long enough for winter conditions. The perfectly normal exhaust gases from the flames of space or water heaters had, as a result of the abnormal drop in outside temperatures, cooled before they could escape into the atmosphere; they had then fallen back down the flue and on to the flame, denying the flame the oxygen it needed to operate normally.
The result? The flame produced carbon monoxide - a colourless and odourless gas that is heavier than air. As the level of carbon monoxide built up, it would eventually reach the level of someone sitting or reclining. The lack of air would cause that person to collapse. A potential rescuer, dropping to floor level to help, would also lose consciousness. Pinkness of the skin is a classic symptom of death by carbon monoxide.
I am prompted to recount this story by the reports of the family of five who nearly died in West Auckland last week from what was reported as "gas poisoning" arising from "petrol-generator fumes". Carbon monoxide is not poisonous in the normal sense. Nor does the fuel that produces the flame have anything to do with it. The records show a case in a tenement building in Glasgow, for example, where someone died when exhaust gases from a coal fire in the room above cooled and fell back down the shared chimney into an open fireplace without a fire. All that is needed is poor ventilation, coupled with a flame that is denied oxygen.
Every year or so, we read of similar cases - in caravans, boats, holiday accommodation. These tragedies will not stop until they are accurately reported.