Tree workers looking for a different style helmet to the popular Petzl Vent or Best should check helmet specifications before they purchase. Helmets used in New Zealand treework must comply with the AS/NZS 1801:1997 standard. The Vent and the Best are both certified to EN12492:2000, a European mountaineering equipment standard and, as such, comply (but are not certified to) the AS/NZ Standard.
In 2009, the British Health and Safety Executive (HSE) recommended the use of mountaineering-style helmets, complying with BS-EN12492:2000, for all aerial tree work operations. While the HSE is specifically UK-based their Safe Working Practice guides are adopted by companies around the world, including New Zealand.Occupational safety helmets generally comply to two separate EN standards: EN12492:2000 (Mountaineering Equipment - Helmets for mountaineers) and EN 397:1995 (Industrial Safety Helmet).
Industrial safety helmets are primarily designed to provide protection to the wearer against falling objects and consequential brain damage and skull fracture.
Mountaineering-style helmets are intended to protect the upper part of the wearers head against hazards but also carry frontal, dorsal and lateral (off-center) shock absorption protection. The test used to measure off-center shock absorption is a 5.0 kg mass weight, dropped from a height of 500mm. Under these circumstances the force transmitted to the head shall not exceed 10.0 kN (this test is not carried out under EN397:1995).
Mountaineering-style helmets are also fitted with a 'chin strap' retention system to retain the helmets on the head and must be able to withstand a force of 250N (In contrast, testing a helmet to EN 397:1995 with chin strap (if fitted) should release with a force not less than 150N and not more than 250N).
Another certification to look out for is ANSI 89.1:2003 Type 1 (or Type II) Class E or Class C.This is an American National Safety Standard for Industrial Head Protection. The Type number refers to lateral impact protection - Type I has no lateral impact protection, Type II does have lateral impact protection. Some helmets can be Type 1 under ANSI but are certified to EN 12492 which covers lateral shock protection. The Class reference under ANSI is more important to tree workers.
Class C stands for Conductive and this class of helmet is not intended to provide protection from electrical conductors - helmets with ventilation holes generally fall into Class C. Class E is designed to reduce the danger from high voltages and is tested to 20,000 V to achieve this rating. For example the Petzl Vent is Class C and the Petzl Best is Class E.
Tree work helmets require one more feature: the facility to attach ear and eye protection (without the wearer drilling holes in the helmet to make this happen!). Ear protection should comply with EN 352 and Peltor and MSA Sordin ear protection equipment comply with this standard and helmets like the Vent and Best have a side slot for attaching ear muffs molded into the helmet shell.
In contrast, the Petzl Elios, which is a popular tree climbing competition helmet, does not have the facility for ear protection. As a recreational sport helmet ear protection is not mandatory but most companies in New Zealand do not allow the Elios because it lacks this feature. Climbers should check their company 'Best Practice" policy on ear protection before they buy the Elios for work!