when unexpectedly hot weather strikes the region with a different temperature conditions, the number of daily deaths is increasing.Although our body and has a number of physiological mechanisms of adaptation to extreme short-term heat, but when the temperature rises too quickly, for acclimatization just no time.Heat waves in London in 1995, for example, caused a 15% increase in the number of deaths.
During heatwaves affected most often children and older people.Older people are at greater risk because the brunt falls on the cardiovascular system, and many older people suffer from cardiovascular diseases.Because of problems with the cardiovascular system, they are not as efficient thermoregulation system as in younger people.It noted the increased infant mortality to 24 hours of life.This is probably due to the fact that their thermoregulatory system is not functioning fully and can not resist heat.
However, most of the deaths caused by the heat wave is due to pre-existing diseases - such as cardiovasc
first encounters a blow of hot weather, our cardiovascular system.With heat blood vessels to dilate, sending more blood to the upper layers of the skin, and of course, that those increases by reducing the raft-convoy Electra skin resistance, so - to increase its thermal conductivity.This is the same reaction that gives our emotions during a polygraph examination.Generally speaking, it is good for the body because it helps to keep cool.But as the blood vessels dilate, blood pressure falls, causing the heart to work harder, pumping blood through the body.So people with already weak heart or performing heavy physical work in hot conditions are at increased risk of heart failure.
During periods of extreme heat can significantly increase the frequency of deaths.Peak mortality usually occurs within 1-2 days after the onset of the peak temperature.Some have suggested that most of those who die during periods of extreme heat, would still have died soon after.But if this were so, then there was a compensating drop in mortality would be in weeks or months after the passage of heat waves.But it is not always to support this data is quite convincing.
However, there is a significant difference between the mortality from the first and second heat waves of the year.The mortality rate during the second heat wave is slightly different from the intended protective effect due to acclimatization.
And the most important factor, apparently, is that if you live in the city or outside the city.The difference of temperature between day urban and rural areas should not be large.However, the night air outside the city cools faster than in the city, as the soil and the grass have a lower thermal conductivity and heat capacity as compared to a brick and concrete of the city.In addition, large urban construction, such as apartment buildings (especially on the upper floors), give off heat more slowly than single-storey houses.As a result, the upper floors of apartment buildings accounts for more victims of heat stroke, compared with one-story houses in the suburbs.
While some researchers argue that the widespread air conditioning reduce the impact of heat waves, the real protective effect on the air-conditioning is relatively small.The air conditioner can at any time to mitigate heat stress.But the global picture of the use of air conditioners has shown that it can become a hindrance work of our adaptive mechanisms, opposing the heat, making people more susceptible to the influence of heat, as they exit the street or in the event of a break in the supply of electricity and air conditioning work stoppage.