professionals - heatwaves - prevention

e-Learning in Heat waves

Professionals

e-Learning for the Prevention, Preparedness and Response to Natural Disasters

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PreventionIn the following you will be presented with information on:

• Description of Heatwaves

• What to be aware of


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DescriptionWhat are heat waves?• Heat waves are a series of days or temperatures that create a

safety hazard for anyone exposed to the heat. A heat wave can be an extended period of days with higher than normal temperatures. A heat wave can also be shorter in length, but with abnormally high temperatures. • Any time a person is exposed to heat, they are in danger of

suffering from heat exhaustion and heat stroke. These heat-related illnesses have killed thousands over the last 100 years.Heat waves characterized by long duration and high intensity have the highest impact on mortality. During the 2003 heat wave the highest impacts were observed in the cities of Paris and London.


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DescriptionThere is no standard definition for a heat wave. In Denmark a national heat wave is defined as a period of at least 3 consecutive days of which period the average maximum temperature across more than fifty percent of the country exceeds 28 °C (82.4 °F). In Lithuania it is if the heat (heat wave) reaches extreme event criteria when the maximum air temperature for 10 consecutive days is 30 ° C or higher.


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DefinitionMost scientists agree that a heat wave is defined as a period when maximum apparent temperature and minimum temperature are over the 90th percentile of the monthly distribution for at least two days. Other scientists define heat waves in more simplified way. They say heat waves are extended periods of unusually hot weather that affect human and animal health as well as energy use.


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Global warmingMore and more scientists claim that heat waves are closely connected with global warming. "Global warming is bringing more frequent and severe heat waves, and the result will be serious for vulnerable populations," said Dr. Amanda Staudt, National Wildlife Federation climate scientist. "That means air pollution in urban areas could get worse, bringing increased risk of heart attacks, strokes and asthma attacks. Children, the elderly, the poor and people of colour are especially vulnerable to these effects."


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Global warmingClimate models indicate that an average summer in 2050 will have even more days topping 32°C. Scientists project that if global warming continues to rise, we will see the following impacts:• More extreme heat waves.• Increased urban air pollution.• More vulnerable natural

habitats.• Negative impacts to

agriculture.


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Global warmingHeat waves have a greater impact on people who are poor, elderly, children, have asthma or heart disease or live in big cities. "Global warming is one of the gravest health emergencies facing humanity. It's life-threatening and it's affecting us now," said Dr. Peter Wilk, MD, executive director, Physicians for Social Responsibility." The science confirms that the frequency and duration of heat waves has increased significantly over the last 50 years. In the United States, heat waves already kill more people during a typical year than floods, tornadoes and earthquakes combined. Given these worsening trends, taking decisive action to stop global warming becomes a medical necessity.“• Watch the video on the next slide to find out what Climate

Change looks like


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Climate changeIn the last decade, hot weather records have occurred three times more often than cold weather records. The climate change is one of the most important reasons for that.Over the past 100 years, heat waves have caused more deaths than any other natural hazard. Heat waves also restrict work capacity and decrease the productivity of exposed workers. Extreme heat can damage infrastructure such as electricity distribution and transport systems, causing follow-on effects.


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Climate changeHot, dry conditions have a major influence on wildfires – these conditions are driving up the likelihood of very high fire danger. Heat waves can cause drought, which in turn can also increase wildfire risk.Additionally heat waves result in high energy consumption, as people use more electricity to power air conditioners in their home, work and cars.


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Climate changeAs greenhouse gases continue to accumulate in the atmosphere, primarily from the burning of fossil fuels, more heat is trapped in the lower atmosphere. If the current trend in greenhouse gas emissions continues through the rest of this century, today’s record-breaking hot weather will become commonplace, occurring almost every summer.


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CharacteristicsHeat waves are a particularly risk for people living in cities because metropolitan areas can be significantly warmer than neighbouring countryside areas. Dense urban areas, such as inner city environments, may typically be 1 to 3°C hotter than surrounding areas. This phenomenon is known as the “Urban Heat Island” and occurs because of a decreased amount of plants and increased areas of dark surfaces in urban environments (sidewalks, roads, etc.). In addition to this is the effect of the heat produced from vehicles and generators. The Urban Heat Island effect is generally more prominent during the night than the day due to e.g. asphalt from the roads that gradually releases heat at night, so it has a great impact on the likelihood of extreme high minimum temperatures.


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CharacteristicsWe can divide the main reasons of why heat waves occur into two parts:1. Air pressureMost of the world's weather systems are powered by areas of high and low air pressure. Heat waves begin with a mass of high atmospheric pressure. The air from the upper atmosphere is pulled toward the ground, creating this system of high pressure. This compresses the air near the surface, which also increases its temperature. Because there is no upward flow of air, clouds do not form, which limits rain and shade. Areas of high pressure also tend to be less windy, which keeps the air mass stagnant. This is why heat waves can last for long periods of time.


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Characteristics2. Depletion of Ozone layerThe Ozone layer covers the Earth and protects it from direct and very harmful sun rays. Depletion of this layer can bring harm not only for people (various cancer illnesses can accur) but also for nature (the land may become drier, the temperature of the air is rising, etc.)We should all be very careful about the environment in order not to make the Ozone layer thinner. However everyone can get into a situation where the heat outside your home may be above the normal temperature. In this case you should all know how to behave and what to do.


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CharacteristicsWe can distinguish several features of heat waves:Unseasonable warmth

Heat waves are generally characterized by periods of unseasonable warmth. This is defined as being at least 9 degrees Celsius higher than the average temperature of a region, during the same time of year.

Although this type of anomaly is common and can also happen during the cooler months, it is generally considered a heat wave during the warm months when the air becomes uncomfortably warm.


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CharacteristicsHumidity• As much as the heat is a factor in a heat wave, so is the

humidity. Humidity measures how much moisture is in the air. Warm air holds more moisture than cold air and, at higher temperatures, humidity can be extremely uncomfortable. The reason for this is that the human body cools itself by the evaporation of sweat. When the humidity is too high, sweat does not effectively evaporate, and people can easily overheat. • The effect of humidity is measured by the heat index, which

describes what the apparent temperature is in high humidity. For example, at 65 percent humidity, a 35-degree day can feel like it's 45-48 degrees outside


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Characteristics• Heat waves, particularly those

with excessive humidity, can accompany and possibly worsen the effects of drought. Heat waves occur when a ridge of high pressure sits over a region for an extended period of time, bringing down dry, hot air to the ground. As the air sinks, it warms and compresses and is very hot by the time it reaches the surface. This hot air quickly heats up the ground, which raises the air temperature well in excess of the average daily maximum.

• Since the centre of high pressure areas are usually cloud-free, the direct sunlight further raises daytime temperatures. If humidity is high, temperatures do not cool much at night. Nighttime heat greatly contributes to heat stress because the body has no relief from the oppressive conditions.


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CharacteristicsDuration

• In addition to unseasonably warm temperatures and high humidity, a heat wave is characterized by its duration. One unusually warm day does not make a heat wave. However, when that heat stays around for two or more days, it is considered a heat wave.

• The longer a mass of high atmospheric pressure sits on an area, the warmer it can get. In this respect, heat waves that last many days or even several weeks can be particularly dangerous.


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Effects on environmentEffects on nature• Like human beings, animals suffer too, particularly when they are left in the direct sun and they do not get adequate water. Domestic animals and poultry are especially vulnerable to heat wave. Temperature, wind speed, humidity, and solar radiation can all contribute to heat stress in livestock. In periods of extreme heat, poultry may lose up to 5% of their body mass per hour and rapidly reach their limit of dehydration tolerance.


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Effects on environmentEffects on nature• Marine organisms are also affected by the impacts of severe heat. Heat

waves can occur in the surface waters of the ocean, sometimes leading to dramatic impacts on marine ecosystems. When coral reefs are subject to sea surface temperatures more than 1-2°C above average summer maximum temperatures, the corals can bleach and die. Bleaching events on the Great Barrier Reef have occurred repeatedly since the late 1970’s, where none were observed before the 1970’s. Bleaching events have contributed to the decline in coral cover observed from 1985 to 2002. However, corals are not the only marine systems to be affected by heatwaves. Mortality and reduced reproduction have also been observed in some marine species. Extreme heat affects each ecosystem differently, however, it may take a long time to recover after the heatwave or the ecosystem may never return to its original state.


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Effects on environmentEffects on nature• Extreme heat has a negative impact on grain crops (maize, wheat, and soya), as well as fruit trees (apple, cherry, pear) and other plants. Many plants and fruit trees can have difficulties because the heat wave may affect the quality of the fruit.


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Effects on environmentEffects on agriculture• Despite the complexity of global

food supply, there are well-established linkages between growing season temperatures, precipitation and crop performance. For wheat, corn and barley, there is a clear negative response of global yields to increased temperatures. Heat waves can have significant impacts on agricultural crops and livestock. High temperatures over several days can substantially reduce the crop yield through both direct and indirect effects.

The direct effect is through:• damage to the crop’s

reproductive parts, responsible for producing grain,

• reduction in productive potential.

Indirectly, extreme temperatures increase:

• plant water stress • photosynthesis, which affects

yield and grain quality, stops functioning and plants could die.


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Effects on environmentImpacts on infrastructure• Extreme heat can have significant impacts on

infrastructure and essential services, especially electricity transmission and transport systems. Heat waves increase the energy demand, in particular from use of air conditioners. Electricity transmission is affected in such a way:Transmission lines may become so hot that they expand and can hang dangerously low. If this occurs, the electricity flow is decreased to allow the transmission line to cool and contract. Ceramic insulators on power lines that are affected by smoke, moisture, or ash from heat wave associated wildfires, become less effective and the electricity supply may be stopped.


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Effects on environmentEffects on wildfires• Fire is a natural and beneficial part of many forest ecosystems, but the number and intensity of fires today is challenging fire managers and forest communities throughout the world. Longer fire seasons will result as spring ends earlier, summer heat builds up more quickly and warm conditions extend further into autumn.


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Effects on environment• Drier conditions will increase the

probability of fire occurrence. Fire was once a healthy, natural part of our ecosystem, however climate change and other pressures are causing more intensified firestorms, causing more damage and putting wildlife more at risk. The impacts on wildlife are:

• They can't escape.• Their habitat is destroyed.• They undergo major stresses trying

to recover.• Bigger fires are changing the

ecosystem balance.


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Impact on humansWorkplace safety and productivity• The effect of extreme heat is the

slowing down of daily activities and reducing work productivity, which is an economically significant factor. Extreme heat can pose serious health risks for outdoor workers and for those working in enclosed indoor spaces without adequate ventilation. Under extreme conditions heat stress or even death can occur. You can divide the physical effort of jobs into three categories affected by heat waves.

Categories:1. Easy physical work – that could be a

job that is closely connected with sitting or less physical activity.

2. Physical job of mid-difficulty – the work connected with bigger physical activity than usual (more walking, more moving) and/or moving things that weigh less than 10 kg.

3. Hard physical job – the job which is connected with permanent and fixed physical activity (walking, moving around, etc.) and/or moving things that weigh more than 10 kg from one place to another.


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Impact on humansThose workers most at risk during a heat wave include:• construction workers • agricultural workers• emergency and essential service workers• those working outside in the mining industry

• Watch the video on the next slide to find out how your body responds to Heatwaves


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Impact on humansAs mentioned before, during physical exertion in periods of extreme heat, the body can have difficulty removing the heat generated. This can lead to the core body temperature rising to dangerous levels, which furthermore can lead to heat stress or death. Extreme heat can also lead to mental health problems in workers, such as:• Aggression and confusion• Psychological distress and other behavioural changes


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Impact on humansThe impacts of extreme heat on workers wellbeing and productivity can also be measured in economic terms, due to the general slowing down or the complete stopping of work. Reduced productivity from future heat waves will not only be costly, but will force changes in the workplace. Measures such as air conditioning to workplaces to enhance worker productivity may be costly and unreliable. Workers may need to take more frequent breaks or work at a slower pace. As a result, to maintain current productivity levels, it may be necessary to:• engage greater numbers of workers.• increase working hours for existing workers.• change working hours to night shifts to avoid the heat of the day.


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Impact on humansPublic healthThe impact of hot weather and heat waves on population health depends upon the level of exposure (frequency, severity and duration), the size of the exposed population and the population sensitivity. It is therefore not surprising that the relationship between daily weather and health varies between populations and between studies.


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Impact on humansEvery year thousands of people suffer from heat stress. Depletion of salt and electrolyte in the body may cause heat cramps and hard work under the direct sun may lead to heat exhaustion.Because men sweat more than women, they are more susceptible to heat illness because they become more quickly dehydrated.

People living in urban areas may be at greater risk from the effects of a pro-longed heat wave than people living in rural regions. While people in rural areas generally get some relief from the heat when temperatures fall at night, urban areas stay warmer.This is as previously mentioned the Urban Heat Island effect.


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Impact on humansMortality rises in hot weather, especially in elderly people. Around 2.000 additional deaths were reported in England and Wales during the major heat wave that affected most of western Europe in 2003. Deaths in Paris increased by 140 %. The sustained period of extreme high temperatures (including the minimum temperature) was unique in the recorded history of Paris and together with housing designed for cooler summers, it caused a major public health crisis.

The recent experience of the heat waves in Europe demonstrated that even in high income countries such events can cause large numbers of deaths in the absence of a coordinated response to ensure that elderly people are kept cool and well hydrated.


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Impact on humansWatch the video on the next slide to find out ; Why do deaths in buildings happen at night during Heatwaves?


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Impact on humansHeat waves or long periods of extreme heat can have serious impacts on people's health. During extremely hot weather, it is easy to become dehydrated (lose too much water from your body), or for your body to overheat. If this happens, you are at risk of developing heat cramps, heat exhaustion or even heat stroke.It is very important that a person’s body temperature stays in the range of 36.1 – 37.8°C. If the body temperature rises above this, a person may develop a heat-related illness.


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Impact on humans• Watch the video on the next slide to see what happens

when you get Heat Stroke


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Impact on humansThe body can lose heat by:• conduction (direct contact of a cooler

object with the skin).• radiation (via infrared rays).• convection (through water or air

circulating across the skin).• evaporation of sweat .When the temperature of the skin is higher than the air temperature, the body can lose heat by radiation, conduction and convection. However, when the air is hotter than the skin, the only means by which the body can lose heat is through sweating (evaporation).


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Impact on humansWhen the weather is very hot, the body has to work very hard and produce a lot of sweat to keep itself cool. Under some conditions, sweating just isn’t enough and a person’s body temperature rises rapidly. This is more likely to happen when it is humid, or when a person is dehydrated and cannot produce enough sweat. In addition, some people cannot cope as well with hot conditions as others. For example, elderly people and people taking certain medications are less able to produce sweat. Also young children produce more body heat, sweat less and have faster rising body temperatures.Exposure to high temperatures can make existing illnesses seriously worse (for example trigger a heart attack), cause serious permanent injuries (damage to the brain or other vital organs) as a result of untreated heat stroke and, in extreme cases, result in death.


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Impact on humansEveryone needs to take care in hot weather, but some people are at higher risk of heat illness. The following are listed characteristics of people at higher risk of serious health effects .Individual characteristics : • Over the age of 75• Infants and young children• Overweight or obese• Pregnant or breastfeeding• Low cardiovascular fitness• Poor mobility• Cognitive impairment• On certain regular medications • Living by themselves or homeless


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Impact on humansSocial characteristics :• Living alone or socially isolated• Low socioeconomic status• Homeless Occupation and recreational activities :• Working in a hot environment (e.g.

labourers, gardeners, fire fighters)• Exercising vigorously in the heatChronic diseases:• Heart disease• High blood pressure• Diabetes• Cancer or kidney disease• Alcohol and other substance use• Mental illness

Conditions that affect sweating:• Heart disease• Dehydration (e.g. conditions causing

diarrhoea)• Extremes of age• Skin disorders (sunburn, prickly heat,

extensive scarring)• Cystic fibrosis• Quadriplegia• Scleroderma• Congenital impairment of sweating• People taking medications with anti-

cholinergic effects Acute illness:• Dehydration (e.g. gastroenteritis, diarrhoea

from other causes) • Infection, especially with a fever


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This educational resource has been produced by the partners of the e-PPR Project (e-Learning for the Prevention, Preparedness and Response to Natural Disasters) with the support of the Erasmus+ programme.

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professionals - heatwaves - prevention

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