The health risks of extreme weather events have been well studied.When temperature is plotted against the number of daily deaths, a typical U-shaped relationship emerges. The middle trough represents a comfort zone where we are not stressed by heat or cold. The right side of the curve shows the death rate increasing with hot temperatures, mirrored by a similar rise in deaths as temperatures drop to extreme cold. And while this winter has had its sub-zero moments, so far it hasn’t produced a prolonged spell of icy conditions.
Older people are especially susceptible to the effects of a cold snap. There is a well-proven link between higher rates of death and cardiovascular disease and a sharp drop in environmental temperature. Other conditions linked to a rise in hospitalisations related to cold weather are hypothermia, respiratory problems and pneumonia.
Research has shown that people aged over 65 are seven times more likely to be hospitalised as a result of frigid temperatures, compared with those aged 18 to 44. And hospitalisations in poorer communities due to cold weather are 2.5 times more common than in the wealthiest neighbourhoods.
Two important parameters help delineate these findings: excess winter deaths and fuel poverty. Excess winter deaths are the number of deaths occurring in the winter months (December to March) compared with the rest of the year. Fuel poverty occurs when a household needs to spend more than 10 per cent of its income on energy in order to maintain an acceptable level of heat throughout the home.
A most interesting study in a recent issue of the journal Environmental Health assessed the relationship between cold temperature and daily mortality in the Republic and the North. It observed strong associations between exposure to cold-weather temperatures and mortality in two adult populations over a period of 24 years. In the Republic it found the impact of cold weather in winter persisted up to 35 days, with a mortality increase for all causes of 6.4 per cent in relation to every drop of one degree in daily maximum temperature. For Northern Ireland the effects lasted for 28 days; a full week less.
The actual causes of additional cold-weather deaths were similar for both parts of the island: heart attacks, strokes, pneumonia and other respiratory diseases were the main culprits. Unsurprisingly, the effect was most noticeable among older people with a suggestion of some gender differences; respiratory deaths were slightly greater among women, while deaths from cardiovascular causes were higher in men.
Commenting on their findings, the authors, led by Dr Ariana Zeka of Brunel University, say: “The fact that the island of Ireland is relatively small, with similar weather, population characteristics and demographics, then any observed differences in the population response to the exposure to cold weather is most likely due to different public policies, socioeconomic construct, and health care systems in the two jurisdictions.”
Which brings us back, among other things, to fuel poverty. Previous research has shown a strong relationship between fuel poverty, social class and geography. At present, there is a concentration of fuel poverty among rural older person households in the North while fuel poverty is highest in the most urbanised and very rural areas in the Republic.
Could the fact that a greater proportion of older people live in social housing in Northern Ireland be significant? Are winter fuel allowances and cold weather payments there more effective than in the Republic? Is the provision of and access to healthcare contributing to the differences in cold weather mortality associations in the two parts of the island?
Let's leave the last word to the authors of the Environmental Health paper: "As the island of Ireland currently has the highest levels of excess winter mortality in Europe, with an estimated 2,800 excess deaths during each winter, the key challenges are to develop and implement policies which tackle fuel poverty and reduce winter morbidity and mortality." mhouston@irishtimes.com muirishouston.com