Much Ado About Noise Pollution
The Issues of Urban Noise, a Noisy Environmental Problem.
∘ Urban Noise
∘ What is Sound?
∘ A Huge Noisy Problem
∘ And What We Can Do?
Urban Noise
It was a peculiar orchestra that it could be heard, the roars of machines that transit full speed over the roads, going and coming from one way to another without rest. The whisper on the air of thousand voices, a duet of horns that discuss between them, the solo crescendo of an alarm, and the noise of a metallic monster that descends from the sky.
The urban noise seems like a weird orchestra we are using to hear daily, it doesn’t matter if it’s day or night. Cities seem to never stop. But, is urban noise a pollutant?
A pollutant could be defined as whatever substance or energy that could produce any harm or disbalance (irreversible or not) to an ecosystem, a physical space, or living things. It is also a negative alteration to the natural environment and is caused by human activities [1]. From this perspective, noise is very likely a pollutant inherent to cities as many others. Since the industrial revolution, the growth of urban settlements, and the increasing use of transport; noise became an important issue to deal with [2].
What is Sound?
Let’s imagine a pool game, where a White cue ball is an object that starts to vibrate, this energy on the ball is transmitted to the other balls (particles) that vibrate as well. This becomes a wave that also transports the energy to other particles throughout the medium until the energy decreases. These waves’ pressure is perceived by our ears as sound. The volume of a sound is determined by its intensity which indicates how much energy is carried by the wave. When sound waves have more energy are louder this could be measured on decibels (dB), a logarithmic scale. This means that is not linear so a sound of 60 dB like a washing machine is not twice a sound of 30 dB like a person talking calmly, is 100 times louder instead.
A Huge Noisy Problem
World Health Organization (WHO) stated acoustic noise as the third most dangerous pollutant just after air and water pollution respectively [3]. Many studies showed that acoustic pollution could cause detrimental effects on humans and wildlife as well. These could be physiological, psychological, and even genetic and has the potential to affect breeding and offspring development, also could produce heart diseases, response stressors, and sleep disturbance [2, 3, 4]. Examples are everywhere, people with learning or memory difficulties, increased aggressive behaviors, anxiety, or stress; many species of animals with reduced survival, unsuccessful reproduction, disorientation, or hearing damage [3, 4, 5, 6]. And these detrimental impacts are just the Surface of the iceberg.
For humans, levels above 55 dB could disrupt fluent communication, chronic exposure between 65 and 80 dB could cause physical hearing damage. For marine animals like whales, the problem is more severe, sound travels faster underwater that’s why many marine animals usually communicate by sound. Nonetheless, the constant traffic of ships, submarines’ active use of sonar tend to affect underwater communication, orientation and even produce injury to these animals. There´s evidence about strandings, stress, shifts in migration paths, changes in diving and foraging behaviors, hearing damage on many underwater animals [7, 8]. A whole unknown world below is affected by us and we are unnoticed.
And What We Can Do?
As you might be thinking, where are the solutions to this environmental problem? Well, there are some attempts to do this (particularly for human welfare). Some of them are the creation of green areas [3]. Some studies suggest that tree belts would disrupt and attenuate sound waves, also provide a habitat for birds and other organisms, purify water, air, and carbon capture [9]. These vegetation walls should be composed of native species and prioritize bigger species that have to be placed closer to noise sources and remote to the interest-protected areas [3].
It is also crucial to regulate the permitted noise levels by developing public policies and educational programs about the impacts of urban noise [10]. There are a set of guidelines for regulation and control of noise that depends on the different areas and human activities, so the industrial and commercial areas are allowed to have a higher average of acoustic levels than residential zones for instance.
Despite these types of policies being already current, there is no interest in fully applying them. That´s why is very common that noise levels overpassed the permitted thresholds. In India, cities exceed specified standard limits above 60 dB at the “calm” places. In Mexico, we have a similar case, not even because we have a law (NOM-081-SEMARNAT.1994) that establishes the maximum limits for noise emission. Just in 2017 Mexican government reported at least 773 complaints (~20%) related to an excess of noise [11]. Like many things, it’s a share responsible between society and authorities.
One way to deal with this problem is having good urban planning: identifying and distancing the areas of greatest noise to the most sensitive like residential zones. Even placing buffer zones like commercial areas. The laws in the Netherlands do not permit the building of houses where average noise levels exceed 50 dB as a measure to attenuate the harmful effects on the population. Another possible solution to control noise is by designing technology or equipment with low noise emission, building noise barriers, and soundproof facilities [10]. But not everything is hunky-dory, noise barriers are a common option but some think that maybe is not enough or could have negative effects like preventing the transit of wildlife or even increasing noise caused by the sound waves echoing off the walls. Is still much research and development for alternatives to mitigate it like “silent pavement” that absorbs sound by adding porous surfaces or quieter tires on transport are just an example [12].
There is still a long way to go in terms of the policies and measures that are carried out for its mitigation. It may be necessary to promote educational campaigns that raise awareness of the consequences and encourage both, the development of technologies that reduce noise emissions, as well as putting into practice responsible urban management and planning that contributes to the well-being of all inhabitants, whether or not they are of the same species.
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