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February 3, 2010

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The hazards of open-air winter work

Blizzards, black ice and buffeting winds have affected most people around the country in recent weeks, and none more so than those who had to go out to work in such hostile conditions. Melvyn French provides a reminder of the havoc winter weather can wreak on open-air work, and the measures that can be taken to mitigate its effects.

The harsh winter weather conditions recently experienced all over the UK prompted a surge of interest in work-related health and safety, as people sought to determine what their own and their employers’ responsibilities were, in terms of getting to and from work, and remaining safe while there. While the views, advice and suggestions offered were many and varied, one thing is clear: the weather to which we are exposed in the course of work certainly can and does affect our health and safety.

Nobody feels very good being soaked to the skin, freezing cold, or sweating buckets in the sun (admittedly not a problem at the moment, but worth mentioning!) Not everyone has the choice to stay at home out of the cold and rain; the work that they do requires them to get on with it, irrespective of what the weather is up to. Inclement conditions can have adverse effects on people’s ability to concentrate, manipulate equipment, move about, use bodily strength, etc, so such conditions do need to be taken into account when drawing up a risk assessment for a job.

Many people work outdoors for a good part of their working day. Examples include those engaged in civil and mechanical engineering projects, highway maintenance (there are said to be 4000 people working on motorways every day),1 street-cleaning and rubbish collection, agricultural/forestry, emergency services, postal delivery, road haulage and delivery people. Some people work in exposed areas (moors and hillsides), others carry out environmental work, e.g. dealing with floods and spillages, and still others are involved in commercial fishing, utility maintenance/services, working on drilling rigs, and in quarries.

The natural climactic conditions and temperatures with which they may have to contend — and the possible effects of that exposure — include the following:

When you are wet through, you may have difficulty moving about owing to slippery surfaces, focusing on tasks, or holding tools. Being wet makes us uncomfortable and therefore less likely to be giving the task in hand our full concentration — employees try to get the job done as quickly as possible so they can go inside to shelter. In addition, wet skin causes the body to cool, losing heat in much the same way as sweating helps cool the body on a hot day.

As well as usually involving heavy rain, there is the threat of being struck by lightning. Obviously, the risk is greater among those who work high up on pylons, communication masts, or inside scaffolding (while the Faraday cage effect2 should protect these employees, it will not safeguard those in the open, or who are working from metal ladders/walkways, or tanks). But the odds of being struck by lightning are very low and would not normally be taken into account. Claps of thunder will make some people jump and hence cause them to momentarily move involuntarily from their work position, which could have serious consequences if, say, they were climbing, or carrying out some delicate manipulation.

Snow and ice
In addition to the problems wrought by low temperatures (see below), snow and ice hamper movement to, from and around a work location, or site. Pedestrians struggle to get from A to B safely, while those who venture behind the wheel are even more at risk of skidding and losing control of their vehicle. As we have seen recently, people take risks — for the best of reasons — to struggle into work. Full praise for the surgeon who must get to the hospital to perform an important operation, but what if they had slipped on the way, and broken their arm? Surgery would have to have been put off for many weeks.

Of course, gritted and/or cleared roads will facilitate movement but what about those who operate the snow plough, gritters, and the first train and bus services of the day?

Bear in mind also that snow can obscure safety signage and underfoot hazards such as potholes, making moving about even more hazardous.

Working in low temperatures can also involve the following hazards:3

  • Frost nip: This is caused by a lack of blood flow to the nose, ears and fingers because they are losing so much heat. Frost nip is an early warning sign, which, if ignored, will lead to frostbite. Frost nip can actually freeze the surface layers of the skin, which means it can easily become damaged without us knowing, e.g. hands can suffer cuts and grazes without being felt.
  • Frost bite: At or below 0ºC (32°F), blood vessels close to the skin start to constrict (this can also occur as a result of exposure to high winds). This constriction helps preserve core body temperature. In extreme cold, or when the body is exposed to cold for long periods, this protective strategy can reduce blood flow in some areas of the body to dangerously low levels. This lack of blood leads to the eventual freezing and death of skin tissue in the affected areas.
  • Snow blindness: Exposure to reflected sunlight from snow and ice, or water — even on grey, overcast days — can result in sunburn of the tissues comprising the surface of the eye, as well as the retina, producing snow blindness.
  • Dehydration: Normally associated with sweating on a hot day, dehydration can also occur in cold conditions. If a large amount of manual work is being carried out while wearing insulated clothing, the wearer will get hot and start sweating. Insulated clothing is designed to retain heat, so sweat does not evaporate and hence the signal given to the body is to produce more sweat. The cycle continues, and because the insulated clothing may absorb the sweat the wearer is unaware of how much fluid has been lost.4 This can lead to dangerous levels of dehydration remarkably quickly, even in sub-zero temperatures.A further complication is that cold air, owing to its physical characteristics (its low retention of heat energy is a function of the lack of moisture — the driest place on earth is in Antarctica!) also tends to be dry air, so each breath we take causes moisture to be lost, further adding to the dehydrating effects of the cold.
  • Hypothermia: This is a medical emergency that occurs when the body loses heat faster than it can produce it, thus causing a dangerously low body temperature. Normal body temperature is around 37°C (98.6°F) and hypothermia occurs as body temperature falls below 35°C (95°F). When body temperature drops, the heart, nervous system and other organs cannot work correctly. Left untreated, hypothermia eventually leads to complete failure of the heart and respiratory system, and thus, to death.Anyone who spends much time outdoors in cold weather can get hypothermia; being wet and tired will also encourage its onset. Even the early stages of hypothermia — disorientation, irrational behaviour and aggression — can have a disastrous effect on the ability to work safely.


By the time wind speeds are up to around 40mph the ability to move around safely is impeded. High winds are a particular issue in relation to work at height — especially crane operations. The Met Office actually provides a ‘tower-crane forecast service’, which gives mean and gust wind speeds (mph, at required heights), wind direction and weather forecasts to construction sites that use tower cranes.

The National Federation of Roofing Contractors in the UK recommends that various types of general sheeting works should be stopped when the wind speed reaches 17-23mph, or gusts from 26-35mph, or stronger. Scaffolding has to be re-inspected after bad weather, or high winds,5 or another event likely to have affected its strength, or stability.

Winds also reduce the temperatures our bodies experience because of the wind-chill factor. Wind chill is the apparent temperature felt on exposed skin due to wind. The degree of this phenomenon depends on both air temperature and wind speed. The greater the wind speed, the faster we lose body heat. Wind chill can make a fairly moderate winter day equivalent to a much colder one — sometimes dangerously so. For example, a day with an air temperature of  -1°C  (30°F) might seem of little concern, but combined with winds of 10 miles per hour, it can feel like it’s -6°C (21°F).


Fog and mist obviously reduce visibility and make operating mobile plant, as well as basic driving, hazardous. People whose tasks take them out on foot into rural areas can become easily disorientated and lost. By its very nature, fog/mist will also involve the hazards associated with wet and cold weather.

Seasonal Affective Disorder

In addition to physical discomfort, bad weather can also adversely affect our mental well-being. Seasonal Affective Disorder (the appropriately acronymed ‘SAD’) is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter — or, less frequently, in the summer — repeatedly, year after year. Sufferers experience a serious mood change when the seasons change. They may sleep too much, have little energy, and crave sweets and starchy foods. They may also feel depressed and hence, work activity and concentration may suffer.

Standing up to the elements

Having taken into account the weather conditions that may assail workers, the next step is to consider possible control measures.

The first, as always, is to decide if the job/task can be delayed until the weather conditions improve. Can the work be programmed to take into account seasonal weather patterns? Can work at night, when temperatures plummet, be avoided?

If work activities do need to proceed, local and up-to-date weather forecasts need to be obtained and disseminated before workers set off. Those working well away from their base and/or in remote areas/off the coast must go well equipped with the necessary PPE, maps and navigational devices, tents, food, water, first-aid kit, torch, whistle etc. (Training will be required on the correct use and/or interpretation of some of this equipment.)

Provision of weather-proof clothing must be made carefully in consultation with the employee, as this is not always the answer. For some tasks, such clothing can be cumbersome and make moving about more difficult. Hence, the material and construction of garments, etc. must be appropriate.

A reliable communication system is also crucial; it’s no good relying on a mobile phone if there is a poor, or absent signal in the area being visited. Some form of lone/remote-worker system is advisable, via which employees can report their expected movements and times so that an employer can keep track of them and be alerted if a time check has been missed. A workable/ proven emergency plan must also be in place and communicated to all relevant staff.

Work in the wet can be dealt with by providing shelter — tents/sheeting, portable huts (containers), work vans, etc. Suitable wet-weather gear will keep an employee dry and comfortable, and allow the level of manoeuvrability required for the task in hand. Remember that the Workplace (Health, Safety and Welfare) Regulations 1992 require provision of suitable facilities for drying clothes — reg.23(c).

Low temperature problems can also be dealt with by providing shelter, where people can warm up and have hot drinks and food on a regular basis. Thermal underwear can be provided, as can other appropriate outside clothing, such as balaclavas, hats and ear-warmers. However, it can be a challenge to keep warm hands that are required to do delicate and intricate manipulations.

In the case of those suffering from SAD, it can be a difficult and sensitive issue to address. Some form of screening within a pre-employment medical and/or understanding by the employer of the condition and the way it might affect any given work task in the winter months can be helpful.

Finally, workers likely to be exposed to the weather conditions described above should be trained to recognise possible events, such as frost bite, hypothermia, dehydration, etc. and provided with information (and first-aid equipment) that will enable them to ward off, or treat these conditions.

Like death and taxes, the weather is unavoidable and is always with us, so those responsible for employees working outdoors must take into account the risks and possible effects on their health, concentration, decision-making processes, and manual activity. Accident figures for individual weather-effected incidents are not readily available (except, perhaps, from insurance companies) but common sense and experience tells us to err on the side of caution when reasonably practicable control measures are available to reduce the risks to and improve the comfort of outdoor workers.

References and further information

1    Institute of Advanced Motorists’ Winter magazine
2    For an explanation of what a Faraday cage is visit
3    For more on the health effects of working in extreme temperatures, see an earlier SHP feature, ‘Freeze a jolly good fellow’, by Dr Chris Ide, in the May 2006 issue (Vol.24, No.5, pp51-54) or visit
4    For more on physiological comfort while wearing protective clothing see an earlier SHP feature, ‘Heat of the moment’, by Dr Wolfgang Nocker, in the February 2008 issue (Vol.26, No.2, pp61-63) or visit
5    BS EN 12811 TG 20:08 — Scaffolding guidance; to find out more, visit
Science of the Cold: How humans deal with and survive extreme cold — Antarctica%20fact%20file/science/cold_humans.htm

Melvyn French is a health and safety advisor with the Environment Agency.

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