Hand arm vibrations

In occupational safety and health, hand arm vibrations (HAVs) are a specific type of occupational hazard which can lead to hand arm vibration syndrome.

Description
Exposure to hand arm vibrations is a respectively newer occupational hazard in the work place. While hand arm vibrations have been occurring ever since the first usage of the power tool, concern over damage due to HAVS has lagged behind its fellow hazards such as Noise and chemical hazards. While safety engineers worldwide are collaboratively working on instilling both an Exposure Action Value and an Exposure Limit Value similar to the occupational noise standards, the Occupational Safety and Health Administration, the only regulatory public safety administration in the United States, has yet to offer either official values in the U.S.

Occupations at Risk
Occupations at risk of Hand and Arm Vibration Syndrome (HAVs) includes Mining, Foundry, and highest exposure being within construction. One unexpected occupation that is associated with HAVs is dentistry. Dentistry is mainly associated with Musculoskeletal Disorder (MSD). Consequently, HAVs is also linked to this field's ergonomic health issues due to the frequent use of dentistry hand-piece tools. As reported by the Vibration Directive of European Legislation, real-time or one-time use of the dental tools does not surpass the exposure limit. However, a long history of frequent handling of these tools has later been associated with Dental workers experiencing HAVs with inclusion of outside factors, such as high Body Mass Index (BMI). While these workplace industries more prominently affect men in the working population, there are still a significant number of women who also experience HAVs. According to a study conducted in Sweden, about 2% of all women and 14% of all men utilize vibrating tools for work. Women are more likely to experience the symptoms for HAVs at a higher prevalence than men.

Suggested guidelines
While OSHA has yet to supply these values, other countries agencies have. The Health and Safety Executive of the British Government suggests to use an Exposure Action Value of 2.5 m/s2 and an Exposure Limit Value of 5.0 m/s2. which is based on the EU directive from 2002. However, it has been shown that those exposure levels still are not safe as 10% of a population would get sensorineural injuries after 5 years at action level exposure. The Canadian Centre for Occupational Health and Safety promotes the ACGIH Threshold Limit Values shown by the adjacent table. When the time-weighted acceleration data exceeds these numbers for the duration, damage from HAVS begins.

There have been additional recommendations based from National Institute for Occupational Safety and Health (NIOSH) to minimize exposure of vibrating tools. Workplaces and Physicians' offices should not only view HAVs as a serious condition but should also look into implementing change. These implementations include engineering control, medical surveillance, and Personal Protective Equipment (PPE) to mitigate vibration exposure. Another implication refers to administrative controls, an example being limiting the amount of hours/days a worker is using the vibrating tools. Furthermore, companies could provide adequate training to workers on the hazards and protocols of handling vibrating tools, along with supplying tools that generate the least amount of vibration while still completing the assignment.

Damage prevention
There are only a few ways to lower the severity and risk of damage from HAVS without complete engineering redesign on the operation of the tools. A few examples could be increasing the dampening through thicker gloves and increasing the trigger size of the tool to decrease the stress concentration of the vibrations on the contact area, but the best course of action would be to buy safer tools that vibrate less. These Exposure Action Values and Exposure Limit Values seem rather low, when compared to lab tested data, shown by the National Institute for Occupational Safety and Health Power Tools Database. Just an example out of the database, the reciprocating saws look to have extremely violent vibrations with one of the saws vibrations reaching 50 m/s2 in one hand and over 35 m/s2 in the other.

There are various occupational standards of vibration measurement for HAV in use in the United States. They are ANSI S3.34, ACGIH-HAV standard, and NIOSH #89-106. Internationally, European Union Directive 2002/44/EC and ISO5349 are the vibration measurement standards for HAV.

Health impacts on industrial workers
Hand arm vibrations can affect anyone that uses them for a prolonged period of time. There are many types of tools that use hand arm vibrations including chainsaws, engineering controls, and power tools. Many industrial workers use these power tools, for example, when working with construction. Some of the side effects of using hand arm vibrations are discomfort in the head and jaw, chest and abdomen pains, and changing speech. Depending on the way the hand arm vibration instruments are held, it can influence the vibration effects. This includes the grip force that the worker uses on the tool, the density of the material the tool is being used on, and the texture of the material the tool is used on. If the material is harder, the vibrations would shake more vigorously compared to a softer material. Hand arm vibrations can also affect people daily with the pain of using these tools such as disturbing sleep, inability to work in certain conditions, and having a hard time doing daily tasks. Hand arm vibrations can affect the daily lives of workers that use these tools.

Reactive monitoring
While there are different tools used to monitor HAV, a simple system can be used in organizations highlighting excess use of grinding disks when using a hand held angle grinder. This is re-active monitoring and it was introduced by Carl West at a fabrication workshop in Rotherham, England in 2009.