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).
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.