Head start

IT IS an unfortunate fact that a significant number of recorded workplace injuries are to the head. Traumatic Brain Injury (TBI) is an injury to the brain that has been caused by a trauma to the head. This type of injury can happen in many areas of life including work, home, and when travelling. Common causes of these injuries include trips and slips, falls from height, contact with a stationary object or structure, and being struck by a moving or falling object. 

There are 57,000 TBI related deaths and 1.5 million hospitalisations in the EU every year¹. TBI has many symptoms, including both physical and physiological effects and their onset may be immediate, or occur days or weeks later. Head protection will offer a degree of protection to the head and it is important that we understand the hazards that do or may exist and select the appropriate head protection to give adequate protection against these risks. 

There are many factors to be considered in the design, manufacture and selection of head protection. These may include:

• Compliance with applicable standards

• Level of protection against impact

• How the forces of the impact are absorbed / transmitted

• User comfort: fit, adjustability, weight, ventilation

• Security on the head

• Other hazards: Heat, cold, high voltages

• Compatibility with other Personal Protective Equipment (PPE)

• Aesthetics

There are numerous safety helmet standards that will help protect workers from a range of hazards such as bumps, falling objects, and blows to the head. Traditionally, Industrial Safety Helmets (EN 397) have been the primary safety helmet for an array of tasks and applications. In recent years, mountaineering helmets (EN 12492), otherwise known as climbing helmets, are becoming a popular choice for working at height applications. Why is this? The standards may help explain their increase in popularity.

Head protection types

Bump caps – EN 812:2012 -Typically a lightweight flexible protection shell, covered with a textile cover with peak. These caps are designed to be unobtrusive, light and comfortable to wear. The bump cap is designed to provide protection against the effects of striking the head against hard stationary objects which can cause lacerations or other superficial injuries. Bump caps are not intended to provide protection against the effects of falling or thrown objects or suspended loads and do not offer the same protection level as an industrial safety helmet as specified in EN 397:2012.
Typical applications include manufacturing, assembly and maintenance operations.

Industrial safety helmets – EN 397 – “Industrial safety helmets are intended primarily to provide protection to the wearer against falling objects and consequential brain injury and skull fracture.” ²
Probably the most commonly used head protection, such as a construction helmet, typically comprising of a peaked hard shell of Acrylonitrile butadiene styrene (ABS) or High Density Polyethylene (HDPE), with an adjustable plastic or textile inner cradle. The shell may incorporate air vents. Chinstraps are optional and may be supplied or fitted retrospectively.

Mountaineering / Climbers Helmets – EN 12492 – “A proportion of the energy of an impact is absorbed by the helmet, thereby reducing the force of the blow sustained by the head.” ³
This type of helmet has its origins in mountaineering where a high degree of protection against falling objects is required. The helmet shells are usually moulded from ABS and are typically peakless, more rounded in shape and extend further on the sides and back. They usually include dense foam protection on the inner shell for enhanced protection and an adjustable textile cradle for comfort and security.

The standards
The Standards describe the test methods and outline the performance requirements needed for a product’s certification. Understanding the key differences may help when selecting the most appropriate head protection to satisfy the risk assessment. The scope of each standard can help explain the aim of the standard.

What are some of the key differences?

EN812 – Bump caps

5kg mass is dropped from a height of 0.25m to the front of the cap, equalling an energy of 12.5J.  
The maximum allowable force transmitted is 15kN 

EN 397 – Industrial safety helmet
5kg mass is vertically dropped from a height of 1m, equalling an energy of 49J.  
The maximum allowable force transmitted is 5kN (note, the equivalent of 500kg).

EN 12492 – Mountaineering helmet
5kg mass is vertically dropped from a height of 2m, equalling an energy of 98J.  
Front, back and sides are impact tested with a 5kg striker dropped from a height of 0.5m with the helmet on an angle.
The maximum allowable force transmitted is 10kN (note, the equivalent of 1000 kg).

EN 50365:2002 - Electrically insulating helmets for use on low voltage installations

Insulation testing to 440Vac is an optional requirement within the EN 397 industrial safety helmet standard but for higher voltages – up to 1000Vac, testing and certification to EN 50365 is required. This standard omits the use of metals in the helmet and places restrictions on ventilation.

Chin strap release force
The mountaineering standard has a mandatory requirement for a chin strap, whereas the industrial safety helmet standard has an optional requirement. In both standards, the chin strap release force is defined and has different performance requirements. The challenge for helmets which are dual certified is how to change the release force required for the anchorage on the helmet shell to fail within the requirements set by each standard.

Selection process

The appropriate head protection should be identified through a risk assessment process with reference to the manufacturer’s product information. As well as establishing the nature and level of impact protection required, all other relative hazards need to be considered e.g. working at height, security of the helmet, contact with chemicals and substances, heat and the presence of high voltages. The comfort of the wearer is also an important consideration, as is compatibility with other items of PPE.

Accessories

As there is often a requirement to use additional PPE to protect against other hazards, it is important that where PPE is used in combination, all items of PPE are compatible for fit and the performance of one item of PPE is not compromised by another. To simplify the combination of head worn PPE, the helmet is often used as the ‘carrier’ for other head worn PPE. 

Examples of equipment that may be fitted to some helmets – subject to manufacturer’s approval, include:

• Helmet mounted hearing protection

• Eye protection through the integration of a drop-down visor or the attachment of visors or screens 

• Communication- in-ear or over-ear communication systems

• Neck protection from weather, debris, splashed liquids or heat.

Some welding helmets and Powered Air Respiratory Protection systems are available with head protection to EN397.

Where combinations of PPE are used, the Duty Holder must ensure that the selected items of equipment are approved and compatible.

Care and maintenance

It is important that, like all PPE, head protection is maintained in a good, safe condition throughout its life. Manufacturers will place a time limit on the life of head protection. This is mainly due to the effects of ultraviolet (UV) light on plastics. The manufactured product lifetime must be adhered to. A helmet should also be withdrawn from service if it is subject to a significant impact, has sustained damage to the shell or cradle, has been contaminated with a substance which will adversely affect the equipment or bears any other indication that the integrity of the item has been compromised.

References