|Moderate noise over long term can damage health
By Ralph Vartabedian
LOS ANGELES - Traffic noise is growing sharply in communities across the United States. The volume of vehicles, particularly heavy rigs, has climbed steeply over the last decade. And people are driving faster, further amping up the noise. Pickups and SUVs, which are significantly louder than cars, are proliferating on residential streets. As well, more vehicles of all types are equipped with noisy, high-performance exhausts and powerful stereo systems.
Activists say the rising din is no mere annoyance. Noise well below levels that damage hearing can increase blood pressure, fatigue and stress, medical studies show. Researchers have found that traffic noise near schools interferes with learning. Moderate but long-term noise - generally over 60 decibels - damages the jealth of children and possibly adults, causing elevated blood pressure, coronary disease, peptic ulcers and higher levels of stress hormones, studies have shown.
Studies in Austria found that school-children exposed to an average noise level greater than 50 decibels learned far more slowly than children in communities with noise below 40 decibels, said Gary W. Evans, a professor of design and environmental analysis at Cornell University who helped conduct the research. "What we have found is that even if noise is not loud enough to damage hearing, it can affect speech recognition," Evans said. "When children live in a noisy environment, they learn to tune out speech and they fall behind."
As the racket grows, people with no escape acquire a sense of hopelessness. In a 1999 census report, Americans cited noise as their most serious complaint about their neighbourhoods. Nationally, noise is the leading reason people want to move. "They call laws that govern noise nuisance laws," said Tom de Stefano, a freelance writer in Toronto who is co-founder of Quiet Please United, which pushes for tougher laws on vehicle noise. "That's a monstrous understatement, like calling kidnapping a petty offence."
|A 1999 federal housing survey in the Los Angeles-Long Beach region found that occupants of 220,000 homes were so troubled by traffic noise that they wanted to move. But for many, moving is an unattainable dream, particularly for low-income people in the noisiest locations. As communities run short of empty land, more housing is being built alongside major highways, a trend evident in fast-growing cities such as Las Vegas and Houston.|
Policy makers in Europe and Asia long ago woke up to noise as a public health problem. European and Asian nations, as well as the World Health Organisation, have set goals for sharply reducing noise from all sources and tightening restrictions on motor vehicles in the next few years. Japan will force its auto makers to reduce car noise by more than 50 per cent by equipping them with quieter tires and exhaust systems. Pickups, large SUVs and other light trucks, which now account for half of all new vehicles sold in the United States, produce twice as much noise as cars, even at relatively low speeds, according to acoustic experts and auto industry representatives.
Among the most politically contentious noise issues is the growing popularity of high-performance exhaust systems, which account for more than $ 100 million in annual sales, according to the Specialty Equipment Market Association, a trade group based in Diamond Bar, California. The modified systems are typically installed by car owners or custom muffler shops. "What I find disturbing is that these companies promote incivility," said Les Blomberg, founder of the Noise Pollution Clearinghouse in Montpelier, Vermont.
Pressure from foreign countries on the auto industry could help curb the decibel level in the United States, said Tim Jackson, senior vice president of global technology for Tenneco Automotive's Walker brand of exhaust systems. "You can already see examples where European and Japanese influence is becoming mainstream in our design of vehicles for North America," Jackson said. "The vehicles coming off the showroom floors today are clearly quieter than their predecessors of 10 years ago."
- Los Angeles Times-The Vancouver Sun