As the sun joins us for longer periods of time and the mercury starts to rise, there is one questions that gets asked by many people - how hot is too hot for work, will they send us home?
Unfortunately, if you're looking for a magic number that lets you go home in the summer the news isn't good - there is no fixed maximum temperature - unlike cold, but that's another post.
This is because factors other than air temperature, like , humidity and air velocity, become more significant and the interaction between them become more complex with rising temperatures. We've all experienced high temperatures that feel nice and comfortable thanks for a nice breeze, or a lower temperature which is almost unbearable because of high humidity.
What the regulations say is:
‘During working hours, the temperature in all workplaces inside buildings shall be reasonable.’
(Regulation 7, The Workplace (Health, Safety and Welfare) Regulations 1992
Reasonable temperature is very dependant on the nature of work being conducted and the environment in which you work.
It all hinges around questions such as;
- is there a direct heat source in the workplace (stove, furnace, oven etc)?
- is the environment humid (a kitchen or laundry room)?
- do employee need to wear heavy PPE?
- is the work very physical?
The easiest way to address this is to conduct a thermal comfort risk assessment, and if there is a risk or heat stress (overheating) then a specific heat stress assessment should be do.
Remember your employees are one of the best sources of information about heat stress and thermal comfort. If a large number are complaining about negative effects of heat then you may be exposing them to an unreasonable temperature!
For many heat stress can be an issue all year round (such as in bakeries, commercial kitchens and foundries) but it is something everyone can be at risk of regardless of their profession during the hot summer months.
When our bodies are exposed to heat they react by increasing blood flow to the skin's surface (this is why we get that lovely red glow when engaging in sporting activities), and by sweating. This results in cooling as the sweat evaporates from the surface of the skin and is carried away from the body, the increased blood flow circulated the excess heat still in the body to the surface to also evaporate in a cyclical process.
Heat can also be lost though direct radiation and convection from the body surface
The more well adapted to the heat we become the more efficient our bodies are at this process.
When our body is exposed to too much heat, or heat levels that it is not well adapted to it can overload this system, or we have caused disruption to this process - this can lead to heat stress.
As well as air temperature, factors such as work rate, humidity and clothing worn while working may lead to heat stress. Therefore it may not be obvious to someone passing through the workplace that there is a risk of heat stress.
You and your employees must be aware of how to work safely in heat, the factors that can lead to heat stress, and how to reduce the risk of it occurring.
An example of a heat stress situation is:Someone wearing protective clothing and performing heavy work in hot and humid conditions for example someone in an engineering factory, a welder in heavy PPE.
- sweat evaporation is restricted by the type of clothing and the humidity of the environment
- heat will be produced within the body due to the work rate and, if insufficient heat is lost, core body temperature will rise
- as core body temperature rises the body reacts by increasing the amount of sweat produced, which may lead to dehydration
- heart rate also increases which puts additional strain on the body
- if the body is gaining more heat than it can lose the deep body temperature will continue to rise
- eventually it reaches a point when the body’s control mechanism itself starts to fail
The symptoms will worsen the longer someone remains working in the same conditions.
What are the symptoms of heat stress? Heat stress can affect individuals in different ways, and some people are more susceptible to it than others.
Typical symptoms are:
- an inability to concentrate
- muscle cramps
- heat rash
- severe thirst - a late symptom of heat stress
- fainting
- heat exhaustion - fatigue, giddiness, nausea, headache, moist skin
- heat stroke - hot dry skin, confusion, convulsions and eventual loss of consciousness. This is the most severe disorder and can result in death if not detected at an early stage
Remember some workers are at more risk than others, these can include;
- pregnant women
- young workers
- employees with existing medical conditions (heart problems, diabetes etc)
- older persons
Much like in all other areas of risk control we need to work down the hierarchy of control, starting with physical controls that protect the many working down to more individual controls.
Not always possible especially for outdoor workers, but one of the first questions to ask is can we control the temperature?
- change the processes
- use fans or air conditioning
- use physical barriers that reduce exposure to radiant heat
Next we can look to provide mechanical aids where possible to reduce the work rate. Regulate the length of exposure to hot environments by:
- allowing employees to enter only when the temperature is below a set level or at cooler times of the day
- issuing permits to work that specify how long your employees should work in situations where there is a risk
- providing periodic rest breaks and rest facilities in cooler conditions
As we mentioned earlier excessive heat causes sweating, our body's natural cooling mechanism, but means losing vital water and minerals that must be replaced. Provide cool water in the workplace and encourage workers to drink it frequently in small amounts before, during (this is not possible in some situations eg respiratory protective equipment use or asbestos removal) and after working.
For workers who are seating a lot, sports drinks can be useful to replace essential electrolytes as well as water - however avoid energy drinks, the high caffeine and sugar will only make things worse.
Think about the type of PPE provided, is their a more breathable or lighter weight option that is as effective, can workers remove it when they are not in an area of risk?
This may help protect workers in certain hot environments. Protective clothing or respiratory protective equipment is often provided to protect from a hazard at work eg asbestos. This type of equipment, while protecting the employee from this hazard may expose the employee to heat stress.
Finally we can provide training for workers, especially new and young employees telling them about the risks of heat stress associated with their work, what symptoms to look out for, safe working practices and emergency procedures.
It is also recommended to allow workers to acclimatise to their environment and identify which workers are acclimatised/assessed as fit to work in hot conditions.
When talking about the rising temperatures in summer we must not forget about the risks of UV exposure.
How many of us reach for sun protection on holiday but then completely forget at work?
The controls are the same whether on holiday or at work.
- wear clothing that covers skin where possible
- avoid direct sun for prolonged times where possible
- avoid direct sun during midday hours where possible
- use UV protection
It's good practice to make sure your workers have somewhere they can take breaks in the shade.
You can't give workers sun cream as this falls into the the realm of prescribing and you don't know about allergies however encourage them to use their own, or even have a box of different choices available for them to use.
Finally if you haven't already, fill out our sign up form and receive free toolbox talks covering heat stress and sun safety plus an attendance sheet, ready for you to deliver to staff to help you manage the risks from heat.
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