London - Should we be counting decibels like we count calories? A growing number of experts believe that loud modern life is making us ill, and that it’s time to go on a ‘noise diet’.
We all know that excessive noise puts our hearing at risk. But increasingly there’s evidence that it affects our health, too.
Typically, the problem is blaring road traffic or the racket of trains and planes, and studies have linked this to high blood pressure, heart disease and stroke.
One Danish study, published in the European Heart Journal in 2011, found that for every ten-decibel increase in nearby road noise, the risk of stroke for those aged over 65 increased by more than a quarter.
Meanwhile, in 2013, researchers at Imperial College London and King’s College London found that people who lived near Heathrow were at greater risk of being admitted to hospital or dying prematurely.
And last week, for the first time, noise pollution caused by road traffic was linked to the growing obesity crisis. Researchers at the prestigious Karolinska Institute, in Sweden, found people who lived near a busy road were more likely to gain weight around their middle than those whose homes were in quieter neighbourhoods.
People who lived under a flight path or near a railway also had a greater risk of being overweight, with those who were exposed to all three types of traffic pollution at double the risk of a larger waist.
So how does noise actually affect health? “Noise is a stressor that raises our arousal levels, influencing the nervous system and hormone levels in the body,” says Stephen Stansfeld, professor of psychiatry at Queen Mary, University of London.
“We are programmed to respond to noise, particularly if it represents a threat — and when we are under stress, the body secretes ‘fight or flight’ hormones including cortisol, adrenaline and noradrenaline, which are designed to get you out of danger.
“But these hormones also raise heart rate, blood pressure and encourage the body to lay down emergency fat supplies.”
Noise can also affect sleep, which in turn has an impact on our health, leading to depression and day-time fatigue, says Dr Anna Hansell, a specialist in environmental epidemiology at the Centre for Environment and Health at Imperial College London.
But it’s not just about volume — Dr Hansell suggests that annoying noises at lower decibels could interfere with human health at a cellular level. One theory is that it stops cells carrying out vital functions such as repair, possibly leading to cell death.
“Although volume counts for a lot, any kind of noise can be annoying, depending on the individual,” explains Professor Stansfeld.
“A person may find specific sounds particularly annoying, such as the hum of a fridge for example, or children crying. It’s the particular tone that’s annoying, rather than the volume. When we carry out research on environmental noise, we ask standard questions to assess an individual’s annoyance levels. It is always subjective.”
An example of this subjectivity is the reaction to children’s noise.
“Noisy children may be a delight to their parents, but often cause misery to neighbours, shoppers or people trying to enjoy a peaceful walk in the park,” he explains.
“Mumsnet forums are full of parents who don’t get why neighbours complain they can’t hear the sound of their own voices.”
Dr Hansell suggests there is no “safe” limit to noise pollution, and that some people are more susceptible to noise and the related health issues than others.
People with tinnitus may be particularly vulnerable. Around 40 percent of tinnitus sufferers have hyperacusis — sensitivity to noise.
So what can you do to reduce the risk noise poses to your health? Here, we look at how to do a “noise diet”.
USE EARPLUGS IN BED
Traffic is one of the main forms of noise pollution, adversely affecting 30 percent of the population, according to the charity Environmental Protection UK.
Traffic sounds include engine noise, car horns, stereos, door slamming and squeaking brakes — a busy intersection can expose pedestrians to up to 85 decibels, the equivalent of working on the average factory floor.
Noisy traffic raises levels of cortisol in the blood, which causes the heart rate to accelerate and pushes up blood pressure. Over time, high blood pressure can lead to cardiovascular disease.
And it’s not just traffic noise in the day that could be a problem — studies show sound can affect you even as you sleep.
According to World Health Organisation guidelines published in 2009, those who are exposed to an average night-time noise of just 40 decibels (the level produced by five cars per minute at a distance of 100 ft) may suffer mild health effects such as insomnia.
Being exposed to more than 55 decibels at night, similar to the din of normal conversation, could trigger high blood pressure and cause heart attacks.
Dr Hansell recommends wearing earplugs while you sleep, and suggests installing double glazing if you live near a busy area, or sleeping in a room that doesn’t face directly towards the road. Even closing a window can reduce noise by 20 decibels.
BUY OFFICE PLANTS
Offices can be noisy places, with phones ringing, shouted conversations and the incessant clacking of keyboards.
Plants can make a difference —research has found that they absorb sound waves, reducing noise.
Hospitals can also be very noisy, which can interfere with sleep and hamper recovery, according to a US study published in the Annals of Internal Medicine in 2012.
It found that people exposed to typical sounds in hospitals found it difficult to sleep because the noise caused the heart rate to accelerate and increased brain activity.
Although noisy sounds were the most disruptive, the study participants — who were healthy — said that the buzz from electronic devices was particularly annoying.
TAKE A NOISE BREAK
Turning the radio or the TV up to tune out distracting noise is just adding to your decibel quota.
“I would avoid this — it might distract you, but it still means you are creating more noise stressors,” says Professor Stansfeld. He explains that stress caused by exposure to environmental noise can be lessened by taking regular noise breaks. In a 2001 pan-European study, he looked at children exposed to high levels of aircraft noise, monitoring their annoyance levels before and after “psychological restoration” in quiet rooms.
He found these breaks reduced reactions to noise, such as poor behaviour, daytime sleepiness and lack of concentration, and improved children’s well-being.
So how might you take a break from the noise around you? One suggestion is to find a quiet space in a park or even the bathroom at home (it is more likely to be soundproof because of the wall tiles and with a smaller — or even no — window).
“It doesn’t have to be deathly quiet,” says Professor Stansfeld.
You could also try humming. Studies suggest that it produces a positive effect on both heart rate and blood pressure. “There is research which suggests that noises of wind and birdsong can increase well-being and reduce stress,” he adds.
When it comes to your hearing health, Dr Ralph Holme, head of biomedical research at the charity Action on Hearing Loss, says that short breaks are important if you are exposed to high decibel levels, for example at a music concert.
“Even a short break of ten to 15 minutes allows the hair cells in the inner ear to start recovering,” he adds. “When exposed to high decibels, these hair cells can be flattened. If you are attending a concert, stand away from speakers and wear earplugs that cut out a significant proportion of the sound.”
Wearing earplugs can reduce average sound levels between 15 to 35 decibels.
WATCH YOUR DIET
“Many factors play a part in obesity and weight gain,” says Emer Delaney, of the British Dietetic Association.
“Living near a busy street may play a role, but most of the evidence points to obesity being linked to diet and how active you are. If you lead a sedentary lifestyle and don’t control portion sizes, you are more likely to be overweight.”
Andrew Hill, professor of medical psychology at the University of Leeds, agrees that environment is a key factor that contributes to psychological stress, but says that over-eating is a “complex biological and psychological interaction”.
“For some people, stress management, such as reducing noise exposure, can help appetite control, but for others, a quiet life is not going to make a difference,” he says.
Eating healthily will also protect your hearing if you’re exposed to extreme noise, according to research just published in the International Journal of Audiology. In the study, more than 2 300 people
had specialist hearing tests and answered questions about their diet. The US researchers found the better the participants’ diet, the better their hearing.
Furthermore, people who ate well but who were exposed to loud noises in their daily lives had similar hearing to people who ate poorer diets but who weren’t exposed to loud noises — the researchers said this showed that a good diet can help prevent hearing damage.
CHECK NOISE LEVELS
A range of apps for smartphones can measure the decibels you are exposed to at home or at work. They use the phone’s microphones to measure ambient sound.
“It can be useful to know what you are dealing with,” says Professor Stansfeld, although it’s important not to worry yourself too much.
“An app can only tell you so much and provide a snapshot.”
Action on Hearing Loss recommends the following apps: SoundMeter+, a free app which provides accurate sound levels and noise exposure readings; and Play It Down, a free iPhone and iPad app that helps assess your hearing ability and how noisy your environment is.
Daily Mail