Controlling exposure to extreme heat in indoor work environments

Controlling exposure to extreme heat in indoor work environments

Working in extreme heat is a known hazard for workers – whether they work indoors or outdoors. It can expose them to the risk of heat-related illness or injury – even death.

Heat-related illness describes a range of progressive heat-related conditions that happen when the body’s normal sweating response can’t cool the body down enough to maintain a healthy temperature. Working in extreme heat in buildings that are poorly designed and ventilated and/or without air-conditioning can expose workers to the risk of heat-related illness. And, the more extreme the heat and humidity, the higher the risk is of serious illness or injury.

Recent climate data shows that workers are now exposed to hotter working environments for longer periods and these more frequent, longer heatwaves may introduce new hazards as well as affect the control options available.

Employers, businesses and other PCBUs have the primary duty of care to ensure the health and safety of workers – regardless of whether they are full-time, part-time, casual, shift workers, labour-hire workers, contractors – or ‘others’ (eg. volunteers, visitors, etc) in the workplace, so far as is reasonably practicable.

You must use the risk management framework to manage any workplace health and safety risks and consult with workers and/or their HSRs at every stage of the process. You must always try to eliminate all identified hazards and their associated risks – including working indoors in extreme heat – so far as is reasonably practicable.

Then you must minimise the remaining risks, so far as is reasonably practicable, following the hierarchy of controls – from top to bottom (i.e. focus on the higher level controls first).

Effective control starts with recognising all potential sources of risk. Usually, a combination of controls is needed to get the best results and any control measures must be determined in consultation with workers and/or their HSRs.

Where a number of different businesses have workers onsite, always consult with all relevant parties – it’s more likely that suitable, long term solutions to extreme heat problems can be found when everyone works together.

SafeWork NSW recommends a workplace heat management plan is developed and implemented, in consultation with workers and/or their HSRs, to effectively manage risks of exposure to extreme heat in at-risk indoor workplaces across NSW.

The plan should include:

  • suitable systems to undertake regular workplace environmental heat risk indicator monitoring (such as temperature and humidity), and
  • designated person/s responsible for monitoring environmental conditions, especially when extreme heat days are forecast
  • details of the extra control measures that are to be implemented in extreme heat conditions; when they are to be implemented; and the person responsible for implementing them, and
  • identified situations where formal workplace heat stress assessments of extreme heat conditions (measuring both environmental and personal factors by an occupational hygienist with skills in assessing indoor thermal conditions and air quality) are necessary.

In some circumstances, during the consultation process with workers, agreement may be reached on specific parameters for extreme heat and other conditions when work will be stopped to eliminate the risk of workers being exposed. All agreed parameters should be included into your workplace heat management plan.

Control measures to consider include:

Eliminate the hazard

In new workplaces:

Workplaces should be designed and built with health, safety and comfort in mind. The best control is to eliminate extreme heat hazards at the design or planning stage when constructing or renovating your workplace. Eliminating hazards at these stages is often easier and cheaper to achieve than making changes later when the hazards become real risks in the workplace.

Safe design of a structure means the integration of control measures early in the design process to eliminate or, if this is not reasonably practicable, minimise risks to health and safety throughout the structure’s life.

To eliminate risks of exposure to extreme heat when designing a new workplace – particularly those that will be without air-conditioning – you should:

  • consider the construction materials to be used for walls and roofs and their impact on heat build-up and dissipation inside the workplace
  • incorporate good air flow for all work areas (eg. via windows, shutters or roof design) to encourage ‘chimney effects’ to help stop the build-up of heat and assist with dissipating it from the structure.
  • incorporate suitable structural insulation to protect persons against extreme heat (and cold)
  • consider workplace design and layout, eg;
    • is installing automated and/or remote-controlled plant and equipment practicable?
    • will the workplace design and/or layout impede ventilation and/or airflow within the workplace?
    • will skylights, doors and/or windows impact on worker’s exposure to extreme heat and direct sunlight?
    • could fixtures and other items impact on air movement (eg. temporary stock displays, stock deliveries, etc)
  • consider the selection and positioning of heat generating plant and equipment
  • consider the velocity and direction of hot air (natural and artificial), including air movement from any heat generating plant and equipment; open windows and doors; and open delivery areas. Also consider potential for air flow within a workplace to be blocked or obstructed, eg: from deliveries received, delivery vehicles, etc)
  • consider:
    • floor surfaces
    • work functions,
    • lighting (natural and artificial)
    • weather, humidity and condensation, and
    • drainage

In existing workplaces:

  • install robotic and/or automated equipment or processes to remove the need for workers to access hot locations; do physically demanding work by hand; etc
  • install remote sensors or other technology to monitor and identify problems in the infrastructure systems of companies (eg. gas, electricity and water supplies) to reduce the need for workers to be exposed to extreme heat in confined spaces.

Isolate the risk

  • isolate workers in air conditioned control rooms away from the hot work environment
  • locate hot processes away from people
  • enclose or insulate hot processes, hot surfaces and around heat generating plant, equipment and pipes
  • install shields, barriers or guards to isolate radiant heat sources, such as ovens, furnaces, etc
  • isolate heat-producing equipment to limit exposure to radiant heat
  • insulate buildings and clad sources of radiant heat
  • where possible, relocate workstations away from hazard areas, such as direct sunlight via windows or skylights etc.

Engineering controls

  • provide air-conditioning to provide cool air, extract warm air, increase air movement, control the temperature and humidity. This can range from small units that lower the air temperature, but don’t control humidity levels or air movement, to large units that can cope with extreme conditions as well as humidity and air movement. Whatever type is used, make sure:
    • there is adequate air flow. Feelings of stuffiness can result when air flow is low, and draughts result when air flow is high
    • the direction of air flow is satisfactory so that the air flow reaches all areas in the workplace
    • the thermostat is not situated directly in front of a vent
    • the air-conditioning unit is regularly serviced and maintained, so it does not break down in the middle of a heat wave
    • outside climate conditions, how workers are dressed and the type of work being done are always considered
  • install local mechanical exhaust ventilation to increase air movement and remove hot or heated air and/or steam from hot plant, processes and areas where heat can build up and/or where there is little air movement
  • provide air-conditioned cabins in cars, mobile plant and other equipment
  • provide evaporative coolers, which operate by passing hot air over water-saturated pads with the water evaporation effect reducing the air temperature and increasing humidity
  • use chiller units, in extreme cases, to relieve air temperature and humidity, eg. when working in confined spaces
  • install reflective or light-coloured external wall cladding and roofing to the building
  • place reflective shields or coatings on radiant heat spots
  • install blinds, louvres, awnings, screens, window tinting treatment, reflective film and the like to windows or skylights etc to control exposure to direct and indirect sunlight. Ensure windows can be opened, where practicable
  • provide fans (eg. desk, pedestal or ceiling-mounted fans) to increase air movement. This may mean providing individual fans to workers or installing banks of fans to ensure adequate airflow. Consulting with an airflow expert may be necessary to ensure effectiveness of banks of fans.
  • provide technology and/or mechanical equipment and aids to reduce the need for strenuous physical work (eg. crane, forklift truck, pallet jack, conveyor belt) for loading, unloading, transferring and order-picking.

Administrative controls

Administrative controls should only be used to provide a systematic framework to support the higher controls that you have implemented.

Administrative actions include:

  • monitoring indoor environmental conditions, particularly during summer and heatwave weather, to help identify and assess the risks of exposure to heat-related illness, as well as monitor the effectiveness of the controls you currently have in place. Where possible, place the read-out so it is easily visible to all staff
  • providing easy access to lots of cool drinking water in each work area and encourage workers to drink often and not wait until they are thirsty
  • providing regular and frequent breaks away from hot work areas and processes in air-conditioned or cool, well-ventilated areas. The frequency and length of the break should be increased if the conditions become hotter and/or more humid, eg: in non-air conditioned premises – up to 30 minutes break every hour, in a cooler area, to help the body cool off. Where relevant, ensure a worker’s break is long enough for them to have time to remove their PPE, have an adequate rest break and then put their PPE back on (if needed)
  • ensuring the first aid room is air-conditioned, where relevant
  • implementing an effective ‘buddy system’ where workers check each other frequently to ensure they are:
    • drinking enough water – a small cup (200ml) of water every 15 – 20 minutes
    • eating regular meals and snacks
    • taking appropriate breaks, and
    • are not showing signs of heat-related illness
  • providing access to crushed ice (to ingest and for use as ice towel) where possible
  • redesign the job to remove an affected worker from a hazard area
  • organising work to minimise physically demanding tasks, eg. conduct work at ground level to minimise climbing up and down stairs or ladders; share strenuous tasks and unavoidable heavier jobs between more workers
  • ensuring the work is paced to meet the conditions. Modify targets and work rates where necessary to ease workloads and reduce physical exertion. Where possible, allow workers to self-pace (set their own work rate) so they are comfortable
  • ensuring workers are acclimatised (used to working in the heat) and not taking medication that will affect their ability to cope with extreme heat. Ease new workers – or those returning after more than a week’s leave – into a hot workplace gradually, allocate extra breaks and slowly increase their workload
  • increasing worker rotation so the same workers are not always exposed to extreme heat
  • reducing the length of shifts. Allow some workers – particularly workers who may be at greater risk  – to leave work earlier if possible
  • providing cooling vests for workers to wear in extreme situations
  • ensuring uniforms are layered, made of breathable fabric that is suitable for the environment and the task. Modify designs, fabrics and/or clothing items to improve suitability of clothing for conditions, if necessary
  • ensuring required dress codes are flexible so workers can adapt their clothing in extreme heat conditions (eg. wear lightweight, practicable short sleeved (even sleeveless) clothing; suitable shorts and/or skirts; not be required to wear jackets or ties etc.)
  • implementing suitable policies and procedures that:
    • ensure a worker with medically-ordered work restrictions can be accommodated, so far as is reasonably practicable
    • allow workers to adjust thermostats or open windows or doors as appropriate
    • allow work schedules to be changed during extreme heat conditions, eg. delay high-risk tasks until the working environment is at a thermally comfortable level, as far as is reasonably practicable
    • ensure appropriate number/s of trained first aiders who know how to deal with heat-related illness are rostered on all shifts
    • manage emergency situations, such as a heat-related illness incident
    • ensure all plant and equipment are regularly inspected, serviced and maintained, eg. air-con in site sheds, any evaporative coolers and fans for use (so they do not break down in the middle of a heat wave); all heat generating equipment (to ensure they are not producing increased levels of heat)
    • conduct workplace inspections at different times of the day to evaluate heat hazards, such as temperature, humidity, work pace, etc
    • where relevant, discuss with your workers and/or HSRs about what personal clothing should be worn underneath any overalls or other protective clothing (as the type and number of extra layers can contribute to a worker being exposed to heat-related illness)
  • implementing effective communication procedures to ensure regular contact with staff working alone
  • providing suitable supervision of all workers. If they must work alone, monitor them and ensure they can easily call for help
  • establishing work-rest schedules and an acclimatisation program, when indicated by a formal workplace heat stress assessment

Suitable information and training must be provided to all workers – regardless of whether they are full time, part-time or casual workers; shift workers; labour-hire workers; or contractors. Ensure the information and training is understood by all workers – including those from culturally and linguistically diverse (CALD) backgrounds. The training content should detail:

  • what the heat management plan is for hot days
  • who the designated person/s are with responsibility to monitor heat and humidity, especially when extreme heat days are forecast
  • how to identify heat hazards in the workplace
  • how to work safely in the heat
  • how to recognise warning signs and symptoms of heat-related illness in themselves or their co-workers; how to respond to them; and when to call for assistance
  • how to avoid experiencing heat-related illness
  • what to do in an emergency, such as a worker experiencing severe heat-related illness
  • how to report heat-related illness incidents
  • that personal factors can increase the risk of exposure to heat-related illness (eg: clothing, hydration, general health, physical fitness, pregnancy, use of some medications, drugs and alcohol)
  • not to replace drinking water with energy drinks, soft drinks or coffee
  • the control measures you have in place to manage the heat risks. Where relevant:
    • ensure they are aware of how the air-conditioning is managed in your building, and
    • explain any roadblocks that may negatively impact on an even indoor temperature.
  • how to use and wear PPE correctly and how to dress for hot conditions. Include any restrictions on personal clothing that can be worn underneath protective clothing, eg. overalls, etc.
  • to consult with their doctor if they have any health concerns.

Personal protective equipment (PPE)

PPE is the last and least effective control in the hierarchy and should only be used to manage any risk that is leftover after all higher-level controls have been implemented, so far as is reasonably practicable.

Wearing or using different types of PPE does not eliminate or minimise any risk – it acts only as a barrier between the risk and the worker.

Workers who need to wear and/or carry PPE in hot indoor work environments can be at greater risk of exposure to heat-related illness because it can increase the body’s heat load.  Wearing protective clothing (such as aprons and overalls) can also increase the risk of workers being exposed to heat-related illness. Where relevant, ensure a workplace policy is developed in consultation with workers and/or their HSRs stating what personal clothing can be worn underneath relevant items of protective clothing, so it doesn’t increase the risk.

Where PPE is provided for indoor workers exposed to extremes of heat, make sure:

  • it is necessary
  • it is suitable for use and approved, where necessary
  • it is made of suitable material / fabric that is designed to keep you cool in a hot work environment
  • it is comfortable to wear, allows free movement of air and sweat evaporation
  • it is compatible to use with necessary equipment and other PPE
  • that workers are wearing it correctly and that they are not wearing more PPE than is required
  • it is task-specific where required, eg;
    • workers exposed to humid heat (eg. in kitchens, laundries) should wear loose fitting, lightweight clothing to assist air movement
    • workers exposed to radiant heat should be supplied with reflective aprons and face shields
    • foundry workers should be provided with a jacket of leather or other suitably flame-resistant material
    • using high-visibility colour options to assist with visibility

Some specialised PPE is available which actively cools the worker and increases the duration for which the worker can operate in hot environments (eg. clothing with gel inserts that absorb heat from the worker’s skin).

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