Spotlight: Climate Change

Health risks, present and future, from global climate change

BMJ 2012; 344 doi: (Published 19 March 2012)
Cite this as: BMJ 2012;344:e1359

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McMichael and colleagues highlight the fact that the effects of climate change have indeed become apparent while mitigation and adaptation measures are still limited. To date and in the future, the major effect of climate change will be related to global warming with greater attention on the health effects of heat; this may lead to an underestimation of the health risk arising from other extreme events. In particular the impact of low temperatures, especially in Mediterranean countries where winters are generally mild and populations are unprepared to cope with these events. Between the end of January and mid February 2012, Italy experienced an exceptional cold spell, with record low temperatures that persisted for 10-18 days. Mean daily temperatures were 10°C lower than the reference period and snow depths of up to 3 meters were recorded in northern and central regions throughout the first half on the month. Entire communities were isolated and cut off from energy and food supplies principally due to the snow.

A first evaluation of the impact of the cold spell conducted in 14 large urban areas showed an increase in mortality only among the 75+ age group, with an overall 1578 (+25%) excess deaths, ranging from +22% in Bologna to +58% in Turin. Figure 1 shows daily mortality and mean temperature trends in Rome and Genoa during the month of February 2012 (data from the National rapid mortality surveillance system, Ministry of Health). In Rome, the increase in daily deaths was concomitant with the decline in temperatures and remained high till the end of the month, while in Genoa the effect was observed after several days from the decrease in temperature.

As stated by McMichael et al., climate change will increase weather instability and the occurrence of extreme heat and cold episodes, even in regions and in populations usually not exposed. Public health adaptation measures are necessary to protect local populations from environmental risks already affecting health, both in the present and in the future. In Italy, like in many other Mediterranean countries, adaptive strategies to prevent cold-related health effects are lacking. Moreover, considering the impact of this recent episode in Italy, it seems important to invest in the definition of a cold plan even in a time of economic crisis and scarce funding for the health sector.

The identification of subgroups more vulnerable to extreme temperatures is important for an effective prevention. Preparedness may be achieved through the introduction of warning systems and local prevention measures modulated on the level of risk and targeted to susceptible subgroups. Informative campaigns are a first important measure to raise awareness among physicians, susceptible subgroups and the general public. Concerning exposure to cold, clinicians and GPs should be aware that exposure to extreme cold temperatures is a risk factor for cardiovascular and respiratory disease and they should consider this aspect in risk prevention and management. For example, the monitoring of patients with previous coronary heart disease during cold days in terms of health conditions and treatment (i.e. aspirin intake, Bhaskaran et al 2010) might represent an important preventive measure capable of reducing the impact of cold exposure in terms of short term mortality.

Bhaskaran K, Hajat S, Haines A, Herrett E, Wilkinson P, Smeeth L. Short term effects of temperature on risk of myocardial infarction in England and Wales: time series regression analysis of the Myocardial Ischaemia National Audit Project (MINAP) registry. BMJ. 2010 Aug 10

Competing interests: None declared

Paola Michelozzi, Epidemiologist

Marina Davoli

Department of Epidemiology, Lazio Regional Health Service, Italy, Via S. Costanza 53, Rome, 00198 Italy

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