Importance of Noise Measurement in Occupational Hygiene

The incidence of hearing loss has grown steadily over the past few decades. Whereas previously, this condition mainly affected the more elderly members of society, it is now equally prevalent among the under-fifties, even affecting those in their teens and pre-teen years. Medications, such as antibiotics and anti-inflammatories, illnesses like mumps and chickenpox, and genetic predisposition can all lead to deafness. However, today, sound is the most common cause. Much of the problem lies with industry, where noise measurement programmes have become an essential first step in protecting workers from this endemic form of hearing impairment.

The condition is knowns as noise-induced hearing loss or NIHL. It is the most common form of deafness and the most frequent source of claims for industrial compensation. NIHL almost certainly existed even before the industrial revolution. However, soldiers returning from the First World War first drew doctors’ attention to the relationship between repeated exposure to loud gunfire and deafness. More recently, noise measurement has gained importance as a component of an industrial hygiene assessment.

Those deafened soldiers led to the birth of a new science known as audiology. It offered the first means to quantify a patient’s hearing loss and determine whether its cause is conductive or sensorineural damage. Nevertheless, it was a further seventy five years before the publication of South Africa’s Occupation Health and Safety Act 85 of 1993. The act required employers to implement any measures necessary to safeguard their staff from work-related injuries and illnesses. Because the latter includes NIHL, accurate noise measurement techniques have become essential to identify and mitigate any significant potential risk to workers’ hearing.

Two of the more worrying features of NIHL are that it is progressive and irreversible. Most people have experienced muffled hearing and tinnitus following exposure to a gunshot or exploding firework. However, after no more than a day or two, the symptoms disappear, and normal hearing is restored. By contrast, when repeatedly exposed to loud sounds, there is no time for recovery, and so, crucial cells in the inner ear can become permanently damaged. Fortunately, accurate noise measurement equipment can identify dangerously high sound levels, allowing employers to implement preventative measures.

Sound levels are measured in decibels, and a normal conversation will typically generate about 60 dB, while a washing machine may produce 70 dB. However, because the decibel scale is logarithmic, that difference of 10 represents a hundredfold increase in sound intensity. Eight hours of continuous exposure to 80 dB is sufficient to cause permanent hearing loss, worsening following repeated exposures. During an occupational health survey, a technician will take ambient noise measurements and may also employ personal dosimeters to monitor individual workers’ exposure.

The Occupational Health and Safety Act places the responsibility on employers to maintain a working environment that poses no significant risk of injury or illness to employees. Identifying hazards, such as missing guard rails, faulty electrical wiring, fire risks, and contaminants in the air or water supply are essential components of the occupation health inspection process. Given the implication of NIHL and the associated compensation claims, noise measurement can be a crucial component of such inspections. To ensure the welfare of your workers and safeguard their hearing, consult IOH Solutions to arrange a professional assessment.