Climate Sense

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isk

oveRnance

and

anaGeMent

ronment of the last few weeks. This means that human adaptability to

continuously changing weather conditions, and thus the variability of the

regional climate, is taken into account. It is important to consider short-

term adaptation because the human body reacts differently to its thermal

environment due to physiological adaptation (short-termacclimatization),

which augments the efficiency of the thermal regulatory system and thus

reduces the thermal load effectively acting on an individual. In addition to

this, short-term behaviour-based adaptation – such as changing clothes

–can reduce the thermal stress acting on the individual. Therefore, epide-

miological studies find lower thresholds for which heat affects human

health in colder climates than in warmer climates, as well as for the begin-

ning of the summer season compared with the end.

DWD calculates the ‘perceived temperature’ in order to assess the

thermal environment of the human being. The perceived temperature is

determined through a simple heat budget model of the human organism,

which includes the main thermophysiologically relevant mechanisms of

heat exchange with the atmosphere. The most important meteorological

parameters included in the model are: air temperature, humidity, wind

speed and radiation fluxes in the short-wave and long-wave ranges. The

short-term adaptation approach is then used to adjust the threshold upon

which a warning is issued. This depends on the meteorological situation

of the past few weeks within a certain range. The thermal load category is

then determinedwith the perceived temperature forecast for 12 UTCused

for the evaluation of heat and the perceived temperature forecast for 06

Heat-related mortality comparisons

Heat-related mortality in comparison to the expected total mortality rate (all age

groups) for different thermal load categories in Baden-Württemberg (1968 – 2003)

Source: C. Koppe, 2005

UTCused to determine cold. During situationswith at least a

moderate heat load (cold stress) totalmortality is significantly

increased.

In order to avoid too many warning situations

per year in Germany, a heat warning is issued if a strong or

extreme heat load is forecasted –where a mortality increase

of more than 10 per cent is expected.

As well as the daytime heat, the HHWS in Germany also

takes night-time air temperature into account. A warning

will only be issued if the night-time temperature does not

fall below the 95th percentile. This additional criterion was

included because the main target of the German HHWS

is the elderly living in nursing homes. Therefore, it is

important to include an indicator for the nocturnal cooling

potential of indoor conditions. To get a better indication

of the indoor environment a thermal simulation model for

buildings was also added. This information is considered

before the biometeorologist decides whether or not to issue

the heat warning suggested by the model. The warning is

then disseminated via the internet to the general public and

by email and fax directly to care homes – as well as to the

health authorities of the Bundesländer, who may decide to

place it on the radio and TVprogrammes of the public chan-

nels. The advice given during a warning depends on the

local health authorities, but targeted advice is usually given

to the general public and to institutions that take care of the

elderly or disabled, such as nursing homes. An evaluation

of the HHWS in the State of Hessen has shown that hospital

admissions due to heat related disorders fromnursing home

inhabitants have decreased significantly since the introduc-

tion of the HHWS.

A precondition for the optimization of a HHWS is that

the system is adapted to national, regional and local require-

ments. These can differ in space and time, even when only

considering the meteorological component. Therefore, it

would be wrong to conclude that one system is superior

to another. Countries that plan to implement or revise a

HHWS have to follow local needs.

Heat advice for the general public

and for nursing home staff

Advice to general public:

• Wear light, loose-fitting clothes

• Drink at least 2-3 litres of water a day

• Avoid alcohol and drinks with caffeine

• Eat only light meals

• Avoid strenuous physical activity

• Stay in the shade

• Wear a hat

• Restrict physical outdoor activities to early morning or evening

• Do not waste water.

Advice for nursing home staff:

• Check room temperatures and if necessary try to cool the room

• Take care that patients drink sufficient water or other liquids

that contain sufficient minerals in order to avoid dehydration.

Be aware that some patients need to be helped to drink

• Check clothes and blankets

• Look for signs of dehydration or other illnesses

• Reguarly check those who can’t care for themselves. Make a

drinking plan and measure body temperature if necessary

• Call the GP immediately if health status deteriorates.