Evaluating cold environments

snowy wrightington

Just a couple of days ago it was the first day of Spring. But it’s more like the middle of winter today in the north of England with heavy snow falling outside which has been blown around by a fairly strong wind. Perhaps the weather is appropriate as this week we’ve been running the BOHS/OHTA Module W502 on the Thermal Environment. And although much of the course is concerned with hot environments, we also cover work in cold conditions.

In general, it’s usually easier to evaluate cold conditions as there are only two environmental parameters that need to be measured – the air temperature and air velocity. Humidity and radiant heat, which are important in hot environments, are less important in the cold. But evaluating the risk is more problematic. As with the heat there are indices we can use and standards we can refer to. The main ones being published by the American Conference of Governmental Hygienists (ACGIH) in their Threshold Limit Values (TLVs) for physical agents. These give work/warm up schedules for a variety of conditions. However as can be seen for the following table the TLVs are really only applicable to very severe conditions that can be encountered working outdoors in places such as Alaska and Canada in the Winter. In the UK outdoor temperatures never get down as low as those in the TLV table. And the coldest workplaces are probably frozen food stores where the temperature will not be less than –30 C with minimal air movement (although this can be, in effect, increased for personnel operating vehicles).

Threshold Limit Values Work/Warm-Up Schedule for Four Hour Shift

Source: CCOHS Canada. Adapted from Threshold Limit Values (TLV) and Biological Exposure Indices (BEI) booklet: published by ACGIH, Cincinnati, Ohio, 2008

So there really isn’t any guidance or standards that are applicable to more temperate climates like in the UK and most of Europe. So how can we evaluate the risk? I think that the answer is that it is mainly a case of using experience, professional judgement and common sense.

Some guidance on assessing cold environments, and an observation checklist, are provided in International Standards ISO 15265 (2000) Ergonomics of the thermal environment: risk assessment strategy for the prevention of stress or discomfort in thermal working conditions, and  ISO 15743 (2008) Ergonomics of the thermal environment – Working practices for cold environments. Unfortunately these, like most standards, are extremely expensive to purchase. There is quite a good paper in the Ingvar Holmér of Lund University in Sweden, Evaluation of cold workplaces: an overview of standards for assessment of cold stress, published in the Journal Industrial Health in 2008 and is available online here

Guidance from the UK Health and Safety Executive (HSE) on cold stress is very limited, referring the reader to various expensive International Standards.  There is a useful chapter in the ILO Encyclopaedia of Occupational Safety and Health chapter on Cold environment and cold work which can be accessed online.

In practice, options for controlling exposure to cold environments, whether outdoors or in workplaces such as food storage and preparation areas, are fairly limited. Appropriate clothing is inevitably going to be one of the main solutions.

Surviving in extreme cold

I watched a TED video today of a talk by Ken Kamler. He was a medic on an expedition to Everest where the climbers were caught out by extreme conditions nearing the summit. Several were killed.  Last week on our BOHS Module course M201  “Thermal Environment and Non-ionising Radiation” we discussed the effects of exposure to cold conditions. This video provides some dramatic illustrations.

One of the climbers caught out on the summit survived unexpectedly. An example of where willpower can lead to someone triumphing against extreme adversity. In his talk, Ken Kamler provides a physiological explanation for this.

Coping with extreme cold

We’re running the BOHS module M201 “Thermal environment and non-ionising radiation (including lighting)” in a couple of weeks.

One of the topics we’ll be covering is cold stress and control of risks to health from work in cold environments.

An interesting blog I’ve been following is reporting on the Catlin Arctic Survey 2010. This is a British led expedition to the Artic who are investigating how greenhouse gases could affect the marine life of the Arctic Ocean. The team will be experiencing temperatures down to  -30oC (by way of comparison, a domestic freezer is only–18º) and wind speeds  of up to 40kph.  There is a real risk of condition such as frostbite  and hypothermia.

The expedition doctor, Martin Rhodes, or “Doc Martin”, will be posting information on the medical aspects of the trip.   A short video interview with him about the hazards to the human body when operating in a polar environment is available on their website here.