Up to 39 ° C in Nimes, 36 ° C in Bordeaux and Voiron, 32 ° C in Paris, 35 ° C in Lyon … 34 departments in a state of orange alarm … In early August, France was covered with a new wave of heat. So what about the impact of this weather on our health 15 years after the terrible 2003 heat wave?
Time for awareness
Everyone has long known that everyday weather conditions like temperature and humidity affect our health. This fact was evident during the heat wave in the summer of 2003: from August 1 to August 18, two-thirds of meteorological stations stably recorded temperatures above 35 ° C. The minimum and maximum rates were the highest since 1950. At night in Paris, the air temperature did not drop below 25 ° C for two days in a row, which did not allow the body to recover from the stress of the heat of the day (and was accompanied by high levels of ozone pollution).
On August 10, after more than a week in the heat, a doctor at the Paris hospital, Patrick Pelloux, raised the alarm in the media, saying that emergency departments were overcrowded and operating in impossible conditions. According to him, the death toll from the heat reached fifty people. Funeral services also reported that they could not keep up with the flow. The refrigerators of the Ryunzhi market were urgently requisitioned for a morgue. On August 13, the Ile-de-France authorities put in place a white plan that allows for urgent summons of doctors and the requisition of hospital beds.
The Ministry of Health denied on August 17 the hypothesis that the number of deaths had increased by 5 thousand, but on August 18 still recognized the possible figure of 3 - 5 thousand. The medical director general was forced to resign. On August 20, the funeral home said it estimated that the death toll in August exceeded the norm by 13,000. The government was unable to confirm these numbers and called for caution.
In fact, the death rate in the country in August 2003 exceeded the average for previous years by 15 thousand people. This was observed in the Ile-de-France and many cities, however, for example, Lille and Le Havre, the trend did not affect. On a European scale, the death toll of the 2003 summer heat is estimated at about 70,000, making it one of the worst ever recorded.
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Decreased life expectancy
The magnitude of the impact depends on many environmental factors (urban heat islands, the density of green spaces, air conditioning …), society and behavior. In this case, we are not talking about a short-term surge in mortality: if only the most vulnerable or suffering from pathologies of the population had suffered from the heat, then the rise in mortality during this period would be accompanied by its decline at the end. Nevertheless, in the months following the heat, nothing of the kind was observed. Thus, in this case we are talking about a real reduction in life expectancy.
During the heat wave of 1976, deaths across the country exceeded the average by 6 thousand people. Not all cases are related to heatstroke or severe dehydration, which is why high temperature is not listed as a cause on death certificates (the same applies to air pollution and other environmental factors). In many cases, we are talking about the decompensation of the existing pathology (cardiovascular, respiratory, renal …): heat becomes an additional factor that leads to death due to a number of reasons.
Underestimated health effects
In France, this heat has demonstrated or confirmed a number of fundamental things. First of all, the heat kills! This environmental factor was outside the field of vision of the sanitary and environmental services. No sanitary agency or public health service has been monitoring to alert people to the heat. There was no coordination between the French meteorological service and the sanitary departments, although the situation later changed.
Fever affects not only those people who are in poor health and are already in the hospital. Three quarters of deaths occurred at home and not in the hospital, probably because the condition and hydration of patients were already closely monitored by doctors. The fight against the heat in France is primarily about preventive measures, and therefore the health care system should not be exposed. Exactly the same logic can be traced among the residents of nursing homes. Alfred Spira's team showed that among people living in such institutions, the effects of heat were more pronounced in those in good health than in those who were not in good health before the hot period.
Finally, the authorities are unable to track the death rate among the population in real time. The alarm is usually triggered by doctors, police, fire and funeral services, even if their assessments are often far from reality. This is not the case in Great Britain, with mortality data available there since the 17th century in less than a week. A decade and a half later, France still does not have the ability to comprehensively track mortality in the country with a lag of a week. The electronic death certificate project could improve the situation. In addition, the Ministry of Health has established a mortality tracking system that covers approximately 80% of the population and collects data from 600 emergency services.
Not all people are equal before the weather
The influence of meteorological conditions is not limited to periods of heat, but is observed during seasonal fluctuations. Based on the time series, we can state a U-shaped relationship between temperature and mortality: the number of deaths increases with positive and negative temperature peaks.
The thermal optimum is about 15-25 ° C, and, deviating from these thresholds, the risk begins to increase depending on the population: the peoples of southern Europe are more susceptible to cold than northerners, and they, in turn, do not tolerate heat well. All this, apparently, is associated with the adaptation of the population to the local climate, which relies on more or less effective protection from heat and cold: heating, insulation, protection from the sun, mutual assistance …
This, of course, does not mean that you can handle everything. When we talk about the effect of temperature on mortality, depending on the thermometer readings in each city, we see that residents of cities in America and countries such as Australia begin to suffer from the heat if it is included in 10% of the maximum values. In Spain, the risk of mortality increases much earlier, already when the average temperature is exceeded. All of this brings us back to the issue of heat adjustment. In addition, the effects of temperature tend to increase with increasing humidity.
Effect of temperature on health
The mechanism of the effect of temperature on health includes both biological effects on the body and effects on the environment and behavior.
In terms of environment and behavior, cold can contribute to carbon monoxide poisoning from boiler rooms, injuries due to icy conditions and the spread of some viral epidemics that are common in cold and dry winter weather.
Direct biological effects on the cardiovascular, respiratory, endocrine, immune and nervous systems. Meteorological factors can also affect pregnancy. For example, it is known that low atmospheric pressure can lead to an underweight baby at birth. This fact has been known for a long time due to the fact that children in Colorado (most of it is located on a hill - lower pressure) are more likely to have low birth weight. Recently, the risk of exposure to weather and in particular temperature conditions on the appearance of premature babies has also been noted.
A few words about measures to prevent exposure to temperature: unlike the fight against air pollution, in which it is hardly possible to somehow do without improving the quality of the environment, we can significantly limit the effect of temperature on health by protecting the body without touching the environment. In case of heat, cooling the body for several hours a day helps to cope with its effects to a large extent. All precautions go in this direction: drink regularly, limit physical activity, and do not go outside during the hottest time.
Surprisingly, at least in our country, these measures are individual in nature: there are no programs that would cover territorial entities. At the same time, the authorities have a lot of tools on hand: open swimming pools for longer and for less money, watering streets, making air-conditioned places more accessible … Such initiatives could complement personal precautions. We do not have exact data on the effectiveness of such measures, but some cities (for example, Grenoble) have begun to develop their own plans for the event of a heat in addition to national ones. These preventive measures are for the most part short-term, although longer-term programs could make our societies more resilient to heat waves:This includes additional greening and an increase in the reflectivity of roofs and road surfaces. Such steps are already being taken abroad and can help local authorities gain a complete picture of the range of different measures, their effectiveness and cost.
Adapting to climate change?
Climate change may lead to an increase in the frequency of extreme weather events (periods of heat or cold, hurricanes). Since 2003, there has been a greater adaptability to heat among the French population. This adaptation is probably due to behavioral changes in the elderly and other changes in our society, rather than physiological processes. This does not mean that society is able to fully compensate for the effects of climate warming, which will manifest itself, in particular, in an increase in the frequency of heat waves. Most likely, not everyone will be able to achieve this.
There is reason to believe that the adaptability of the population (the resistance of societies and urban areas) to heat varies from region to region. In addition, scientific studies indicate that between 1993 and 2006, Japanese and American cities became less susceptible to heat, which is not to say about the British. In particular, we have data on New York for the entire twentieth century. They point out that temperatures of 29 ° C led to a 43% increase in mortality between 1900 and 1909 (37-49%, 95% CI). At the same time, in the period from 2000 to 2009, the growth decreased five times, to 9% (5-12%).
Air conditioning is not an option
New York's rise to heat resistance throughout the 20th century looks like good news. In any case, these results were achieved in part due to the proliferation of air conditioners and personal vehicles (with air conditioning). Almost 90% of American homes have air conditioners that consume energy (that is, contribute to the production of greenhouse gases) and for a long time emit chlorofluorocarbons, which are thousands of times stronger than carbon dioxide in terms of generating the greenhouse effect and depleting the ozone layer.
Chlorofluorocarbons have been banned from American air conditioners since the mid-1990s, but most manufactured before 2010 still use difluorochloromethane, which has an equally potent greenhouse effect.
The factor that makes American society more resistant to heat is also responsible for the fact that it emits the most greenhouse gases per inhabitant. Thus, the spread of this model to the entire planet is alarming.
Rémy Slama