Keep quiet, please!

Noise pollution has not received as much attention as other types of pollution, such as air pollution, or water pollution. This is because the fact that we can’t see, taste or smell it; however, the air around us is constantly filled with sounds. (Noise Pollution, 2012)

Noise is “unwanted or disturbing sound”.  Sound becomes unwanted when it either interferes with normal activities such as sleeping, conversation, or disrupts or diminishes one’s quality of life.  The persistent and escalating sources of sound can often be considered an annoyance. This “annoyance” can have major consequences, primarily to one’s overall health. (Noise Pollution, 2012)

The inner part of the ear contains tiny hair cells. The hair cells change sound into electric signals. Then nerves carry these signals to the brain, which recognizes sound. These tiny hair cells are easily damaged by loud sounds and too much use and it may become damaged. (Vorvick, 2012). The risk of damage to hearing depends on volume which is measured in decibels (dB), duration of exposure (Stony Brook Surgery, 2012) and family history of hearing loss. (Vorvick, 2012)

Figure 1 How sound is transmitted

Source: (Macrae, 2010)

Noise pollution not only causes hearing problems. Nonauditory effects of noise exposure are those effects that don’t cause hearing loss but still can be measured, such as elevated blood pressure, loss of sleep, increased heart rate, cardiovascular constriction, labored breathing, and changes in brain chemistry. According to the WHO Guidelines for Community Noise, “these health effects, in turn, can lead to social handicap, reduced productivity, decreased performance in learning, absenteeism in the workplace and school, increased drug use, and accidents.” (Chepesiuk, 2005)

Noise pollution also affects the ecosystem. It has been found that noise can have a number of impacts on wildlife such as changing patterns of behaviour and effects on breeding patterns. (An Economic Valuation of Noise Pollution – developing a tool for policy appraisal, 2008) For example, increased mortality was observed in fish eggs and embryos located in environments with ambient noise levels that were only 15 dB higher than those observed in nature. (Banner & Hyatt, 1973)

Figure 2 Black-chinned hummingbirds appear drawn to noise, perhaps because their predators, scrub jays, leave noisy sites

Source: (Parry, 2012)

In Singapore’s context, the noise pollution is a common problem from construction sites and Mass Rapid Transit (MRT). Can you imagine the life of residents who have to withstand the noise from MRT trains whizzing by their homes?

One of the operators of MRT train, install noise barrier as mitigation measure. SMRT Trains Ltd (SMRT), have completed installing noise barriers at the new MRT viaduct at Jurong East Station and near Bishan Station. It expects that some 20km of noise barriers may be needed in all to reduce noise pollution from its train network and the installation should be completed by 2020. (Land Transport Master Plan 2013, 2013) The noise barriers will help to reduce noise levels from passing trains by about five to 10 decibels. (REDUCING RAILWAY NOISE, 2013) The current noise guideline adopted to guide developments in the vicinity of MRT tracks is 67 dBA (equivalent continuous noise level over 1 hour) at the facade of building.

Figure 3 Noise barrier installed by SMRT

Source: (Land Transport Master Plan 2013, 2013)

Is the noise level of 67dBA (continuous exposure for 1 hour) safe that it does not cause any health impact?

If a sound reaches 85 dB or stronger, it can cause permanent damage to your hearing. The amount of time you listen to a sound affects how much damage it will cause. The quieter the sound, the longer you can listen to it safely. If the sound is very quiet, it will not cause damage even if you listen to it for a very long time; however, exposure to some common sounds can cause permanent damage. With extended exposure, noises that reach a decibel level of 85 can cause permanent damage to the hair cells in the inner ear, leading to hearing loss. (Decibel Exposure Time Guidelines)

Figure 4 Permissible exposure time for different sound levels

Source: (Decibel Exposure Time Guidelines)

It seems that noise level of MRT is less likely to cause hearing impairment, but it is possible to cause annoyance. The same noise could be annoying to some people but acceptable to others. There is no definite relationship between the degree of annoyance or unpleasantness of noise and the risk of adverse health effects. (Noise - Non-Auditory Effects, 2007)

Maybe for some of the people, the noise produced by MRT is the alarm clock?

Works Cited

Noise - Non-Auditory Effects. (2007, February 16). Retrieved September 19, 2014, from Canadian Centre for Occupational Health and Safety: http://www.ccohs.ca/oshanswers/phys_agents/non_auditory.html

(2008). An Economic Valuation of Noise Pollution – developing a tool for policy appraisal. United Kingdom: Department for Environmental Food and Rural Affairs.

Noise Pollution. (2012, July 16). Retrieved September 12, 2014, from U.S. ENVIRONMENTAL PROTECTION AGENCY: http://www.epa.gov/air/noise.html

(2013). Land Transport Master Plan 2013. Singapore: Land Transport Authority.

REDUCING RAILWAY NOISE. (2013, May 17). Retrieved September 13, 2014, from Land Transport Authority: http://www.lta.gov.sg/content/ltaweb/en/public-transport/mrt-and-lrt-trains/reducing-railway-noise.html

Banner, A., & Hyatt, M. (1973). Effects of Noise on Eggs and Larvae of Two Estuarine Fishes. Transactions of the American Fisheries Society, 102,134-136.

Chepesiuk, R. (2005, January). Decibel Hell: The Effects of Living in a Noisy World. Retrieved September 13, 2014, from National Center for Biotechnology Information: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1253729/

Decibel Exposure Time Guidelines. (n.d.). Retrieved September 14, 2014, from Dangerous Decibels: http://www.dangerousdecibels.org/education/information-center/decibel-exposure-time-guidelines/

Macrae, F. (2010, May 14). Deafness cure breakthrough as scientists create tiny ear hairs from stem cells. Retrieved September 14, 2014, from Daily Mail: http://www.dailymail.co.uk/health/article-1278160/Deafness-cure-breakthrough-scientists-create-tiny-ear-hairs-stem-cells.html

Parry, W. (2012, March 20). Human Racket Affects Plants, Too. Retrieved September 13, 2014, from livescience: http://www.livescience.com/19189-noise-pollution-indirect-effects-plants.html

Stony Brook Surgery. (2012, August 23). Headphones & Earphones Can Cause Permanent Hearing Loss: What You Need to Know. Retrieved September 13, 2014, from Stony Brook School of Medicine: http://medicine.stonybrookmedicine.edu/surgery/blog/headphones-and-earphones-can-cause-permanent-hearing-loss-what-you-need-to-know

Vorvick, L. J. (2012, May 13). Hearing loss and music. Retrieved September 13, 2014, from MedlinePlus: http://www.nlm.nih.gov/medlineplus/ency/patientinstructions/000495.htm