Shining light on accidents

"Accidents," said Mr Micawber in Dickens's David Copperfield, "will occur in the best regulated families

"Accidents," said Mr Micawber in Dickens's David Copperfield, "will occur in the best regulated families." They may, he went on, "be expected with confidence, and must be borne with philosophy." But some accidents, it seems, are more likely at certain times of year than they are at others, and there is also good reason to believe that the weather may have a bearing on their frequency.

Some years ago, a trio of Irish orthopaedic surgeons produced a study which related the occurrence of fractured limbs to certain types of weather. The research of Messrs Borton, O'Brien and Masterson was based on an analysis of 1,122 admissions involving broken bones to the Children's Hospital, Temple Street, in Dublin, over a three-year period from January 1988 to December 1990. The object of the exercise was to see if there was a relationship between the frequency of injuries such as these and the weather prevailing at the time.

Not surprisingly, perhaps, the first point to emerge was that, whatever the weather, boys seem to break more bones than girls; the ratio is close to 3:2. The second finding was that there is a definite seasonal variation to the incidence of fractured limbs, with a marked peak occurring from May to August, and a corresponding trough from Christmas through to February; fractures were found to be more than twice as common in the summer months.

Their next focus was to try to identify which weather elements affect the issue. This was accomplished by comparing the admission rates at Temple Street with detailed weather observations from nearby Dublin Airport. Rainfall was found to have some effect upon the numbers, in that there were fewer injuries when it was wet. But when the sunshine figures were examined, a much stronger relationship was found: on days when the number of hours of sunshine was above average, the average admission rate more than doubled compared to cloudy days.

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These findings may not seem all that surprising. Obviously children are more likely to suffer injuries involving broken bones when they are out of doors and engaged in robust physical activities, and the opportunity and inclination for these fun and games increase when it is dry and sunny. But factors other than the weather may play a part as well: the number of hours of daylight has a bearing on the risk exposure and, so the surgeons say, bones are more fragile during spells of rapid growth - and the adolescent growth rate peaks during the spring and early summer.

Nonetheless, it is comforting to see reality, expressed in numbers, reflecting intuition.