MY mother loves to tell me of the time she almost had a heart attack while attending a “noisy” church service.

“I felt the noise in my heart!” she would say.

Noise is an unwanted sound. We are exposed to it in our homes, offices, in our cars, and in public places. As our population grows, noise pollution increases and this has tremendous public health implications, affecting us without our being aware of it.

The World Health Organisation has documented seven categories of noise pollution’s adverse health effects on humans.

1. Hearing impairment

Hearing is essential for our well-being and safety. Exposure to sound levels less than 70 decibels (dB) does not produce hearing damage, regardless of the duration of exposure. However, exposure for more than eight hours to sound levels in excess of 85 dB, which is roughly equivalent to the noise of heavy truck traffic on the road, is potentially hazardous.

Studies suggest that children are more vulnerable to noise-induced hearing impairment. Many young schoolchildren and teenagers use devices with earphones or headsets for extended periods of time and at potentially dangerous volume settings. The use of these devices may be responsible for the impaired hearing that is being seen with growing frequency in younger people. Musicians, club and bar workers are also at risk for hearing impairment. We have to remember that ears do not get used to loud noise – they get deaf.

2. Interference with spoken communication

Noise interferes with the ability to understand normal speech. Noise may lead to fatigue, irritation, problems with concentration, decreased working capacity, stress reactions, accidents, and poor academic performance. Children and the elderly are particularly vulnerable.

3. Sleep disturbances

Environmental noise is one of the major causes of disturbed sleep. Chronic sleep disruption causes mood changes, decrease in performance and other long-term effects on health .

4. Cardiovascular disturbances

Chronic noise burden is associated with the risk of heart attack.

A study by Dr Stefan Willich looked at 4,115 heart attack survivors, mainly men in their mid 50’s, from 32 major hospitals in Berlin between 1998 and 2001. Patients rated their daily noise exposure in the years before their heart attacks along with their annoyance at that noise. They were compared with patients from the same hospitals who had not experienced a heart attack. The study found that chronic noise was linked to a “mildly to moderately” increased heart attack risk.

Noise was not solely responsible as smoking, diabetes, high blood pressure, and elevated cholesterol levels raised the risk of heart attack. Dr Willich commented that combining those risk factors could be a bad mix. For example someone who smokes and works in a noisy office could have a higher heart attack risk.

5. Disturbances in mental health

Noise pollution may contribute to anxiety, stress, nervousness, headache, emotional instability, increase in social conflict, impotence, and psychosis. Children, the elderly, and those with underlying depression may be particularly vulnerable to these effects. Noise levels above 80 dB are associated with both an increase in aggressive behaviour and a decrease in helpful behaviour.

6. Impaired task performance

Researchers found that noise exposure was significantly related to problems in the classroom and mental health issues in children – the longer the exposure, the greater the effect. Children who live in noisy environments have been shown to have elevated blood pressures and elevated levels of stress-induced hormones. These changes were greater in children with lower academic achievement. This would suggest that schools and daycare centres should be located in quiet areas.

7. Negative social behaviour and annoyance reactions

Annoyance is a feeling of displeasure associated with any agent or condition believed by an individual to adversely affect him or her. Annoyance increases significantly when noise is accompanied by vibration, low frequency components or when it contains impulses such as the noise of gunshots. In combination with provocation, hostility, alcohol, or other psychoactive drugs, noise may trigger aggressive behaviour.

Noise and pregnancy

Excessive noise may have damaging effects on a developing foetus. Many pregnant women are exposed to noise in the workplace. In one study, the children of women exposed consistently to high levels of occupational noise during pregnancy were more likely to have high-frequency hearing loss, which is identified at four to 10 years of age, than children whose mothers were not exposed. This, of course, should be of concern to pregnant women who are living or working in noisy environments.

Dr Jacqueline E Campbell is a university lecturer and family physician. She is the author of the book A patient’s guide to the treatment of diabetes mellitus.