NOISE POLLUTION SOURCES EFFECT CONTROL OLUWADARE T DEPARTMENTS

NOISE POLLUTION : SOURCES, EFFECT & CONTROL OLUWADARE, T. DEPARTMENTS OF COMMUNITY MEDICINE & PUBLIC HEALTH

Introduction • Noise is – unwanted sound – Wrong sound, in the wrong place, at the wrong time. • Noise has become a very important stress factor in recent time. • Noise pollution signify the vast types of sounds that are being produces in the modern life, leading to health hazards

Properties of sound • Noise has two important properties – Loudness or intensity – Frequency • The effect of sound is subjective, that is different people responds differently to perceived intensity rather than the loudness of the sound.

Properties of sound contd. • Loudness – loudness of noise is measured in decibels (d. B). – Normal conversation produces a noise of 60 -65 d. B – Whispering is 20 -30 d. B – Heavy street traffic is 60 -80 d. B. – A daily exposure up to 85 d. B is about the limit people can tolerate without substantial damage to their hearing.

Properties of sound contd. • Frequency – Frequency is denoted in Hertz (Hz) – The human ear can hear frequencies from about 20 to 20, 000 Hz , this range reduces with age and other subjective factors. – Range of vibration below 20 Hz are infra-audible and those above 20, 000 Hz are ultra-sonic. • Phon is psycho-acoustic index of loudness, it takes into consideration intensity and frequency.

Noise measurement • The basic instrument to study noise are – Sound level meter- measures the intensity of sound in d. B – Octave Band Frequency Analyzer- measures noise in octave band – Audiometer- measures hearing ability

Sources of noise • Student activity • Mention the different sources of noise

Effects of noise exposure • The effects of noise exposure are of two types – Auditory effects – Non-Auditory effects

Effects of noise exposure • Auditory effects – Auditory fatigue: It appears in the 90 d. B region and greatest at 4000 Hz. It is associated with whistling and buzzing in the ear. – Deafness: The hearing loss may be temporary or permanent. Repeated or continuous exposure to noise around 100 d. B and above may result in permanent hearing loss.

Effects of noise exposure • Non-Auditory effects – Interference with speech: noise interferes with speech communication when it is between 300500 Hz – Annoyance: neurotic people are more sensitive to noise than balanced people. Workmen exposed to higher intensity of noise in occupational capacities, were often irritated, short tempered and impatient.

Effects of noise exposure • Non-Auditory effects – Efficiency: reduction in noise has been found to increase work output. – Physiological changes: there a number of temporary physiological changes occur in the human body as a result of exposure to noise. These are: • • • Rise in blood pressure Rise in intracranial pressure Increase in heart rate and breathing Increase in sweating. Nausea Fatigue

Control of noise contd. • Careful planning of cities – Cities should be divide into zones with separation of areas concerned with industry and transport – Separation of residential areas from the main streets by means of green belt areas. House fronts should lie not less than 15 meters from the road and the intervening space should be thickly planted with trees and bushes.

Control of noise contd. • Control of vehicles – Heavy vehicles should not be routed into narrow streets. – Vehicular traffic on residential streets should be reduced. – Indiscriminate blowing of horn and use of pressure horn should be prohibited.

Control of noise contd. • Improve acoustic insulation of building – Installations that produce noise or disturb the occupants within dwellings should be prohibited – Buildings s should be sound-proof where necessary

Control of noise contd. • Protection of exposed persons – Hearing protection is recommended for all workers who are consistently exposed to noise louder than 85 d. B in the frequency bands above 150 Hz. – Workers must be regularly rotated from noisy areas to comparatively quiet posts in factories. • Legislation • Education

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