PLANT MANAGEMENT
WHEN DOES NOISE BECOME HARMFUL? It’s widely recognised that extended exposure (eight hours or more) to noise levels of 85 decibels (dB) or above is likely to have a detrimental effect on someone’s health. To put that into perspective, it is the equivalent to the noise level of city traffic heard from inside a car (so if you’re turning your stereo up to drown out the noise, you could be harming your health). Put another way, the noise level is about 80dB if people have to raise their voices to be heard at a distance of 1m and it is about 90dB if people have to shout to be heard at the same distance. Compared to many industrial processes that is not an excessively loud noise, which shows the depth of the problem. The most commonly considered impact of excessive noise is hearing loss. Although this is a serious and life-changing condition, it is far from the only physical, psychological or emotional effect exposure to noise has on workers. Issues that can arise include sleep disturbance, cardiovascular disease, fatigue, nervousness, frustration or aggression. The impact on businesses can also all too often
be under estimated. As well as the costs of personal protective equipment (PPE), productivity can be lower when communications are interrupted by noise or workers require sick leave. If the health problems are long term there is also the potential for costly legal action.
INFORMATION IS POWER Like many processes, reducing noise levels requires data - the more there is available, the better the solution will be. Once information on noise is gathered, whether from dosimeters, manufacturers’ specifications, software libraries or any other source, a noise map can be created that shows the source, levels and propagation of noise inside and outside a facility. Using the noise map, it is possible to model not only
current noise levels but also projected ones. This means that noise can be mapped and mitigated at the plant design stage or once it is up and running. It’s worth remembering that while individual machinery may not exceed limits, the cumulative impact of a process can be deafening.
Noise maps are a very visual demonstration of the
issues (they are colour coded so can be understood by anyone), which can be useful, especially when dealing with the local community or non-engineers involved in the project. Mapping software can also break down different noise components rather than just giving an overall figure as a measurement does. With this approach noise mitigation can be targeted in the most cost efficient way.
APPROPRIATE STEPS Modifying or replacing the noisiest equipment is usually the most effective way to help safeguard workers’ health. As this isn’t always possible, the next best step is to adapt the environment around the equipment. This can mean installing barriers or insulation measures at the appropriate points. These may seem relatively simple steps, but they
Noise maps are a visual demonstration of the issues relating to sound
can have a huge impact on people’s lives and businesses success rates. At the very least, companies need to ensure they clearly mark and signpost the areas where workers or visitors are at risk of exposure to excessive noise and ensure that the required PPE is available.
IGNORING NOISE IS NOT AN OPTION Alongside general health and safety regulations that should protect workers, most industrial nations have specific noise rules, such as the EU’s Environmental Noise Directive or the UK’s Control of Noise at Work Regulations. This national legislation requires noise control measures to be in place so that the lowest reasonable levels of noise emission and noise exposure is achieved. According to the USA’s Occupational Safety and
Health Administration (OSHA), last year US businesses paid more than US$1.5 million in penalties for not protecting workers from noise. The organisation stated that, “While it’s impossible to put a number to the human toll of hearing loss, an estimated US$242 million is spent in the USA annually on workers’ compensation for hearing loss disability.” Protecting workers from excessive noise makes sense
morally and financially. Therefore, when developing the industrial processes that create the products we depend on – including clean water, plastics and food and drinks – process engineers should also consider the people who will be working in the environment they create. The benefits of doing so should be music to everyone’s ears. n
Arne Berndt is owner/adviser at SoundPlan.
www.soundplan.com/noise-control.htm
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