NOISE POLLUTION BELLO C B INTRODUCTION Noise has

NOISE POLLUTION BELLO C. B

INTRODUCTION • Noise has become a very important “stress factor” in our environment. • The term noise pollution has been recently coined out to place attention to harsh and unpleasant sounds that are being produced in this modern day which has lots of health hazards.

DEFINITION • Noise is commonly called an unwanted sound, but this definition is subjective because a sound that seems unwanted to someone may be pleasant to another person. • Noise is defined as “a wrong sound, in the wrong place, at the wrong time”.

SOURCES OF NOISE • • • Automobiles Factories Industries Aircrafts Railways Loudspeakers of churches/ mosques Radios Televisions Loudspeakers of music on streets etc Man and animals

PROPERTIES OF NOISE § LOUDNESS § FREQUENCY

LOUDNESS • Loudness refers to the intensity of the noise which depends on the amplitude of the vibration that initiated the noise. • The loudness of noise is measured in decibels (d. B). • Normal conversation noise- 60 -65 d. B • Whispering- 20 -30 d. B • Heavy street traffic- 60 -80 d. B • Motor car horn-120 d. B • Boiler factories- 120 d. B • A daily exposure that an individual can tolerate without damage to the ear is 85 d. B

LOUDNESS CONTD • • Speech 2 -3 people- 73 d. B Speech on radio- 80 d. B Music on radio- 85 d. B Children shouting-79 d. B Children crying- 80 d. B Vacuum cleaner-76 d. B Piano -86 d. B Jet take-off- 150 d. B

FREQUENCY • This is denoted by as Hertz (Hz) • Human ear can hear frequencies from about 20 to 20, 000 Hz but this range is reduced with age and other subjective factors. • The range of vibrations below 20 Hz are infraaudible, and those above are ultra-sonic • Some animals can hear sound that are inaudible to man.

INSTRUMENTS FOR MEASURING NOISE • Sound Level Meter- measures the intensity of sound in Db. • Octave Band Frequency Analyser- measure noise in octave bands • Audiometer- measures hearing ability

EFFECTS OF NOISE EXPOSURE • AUDITORY EFFECTS • NON-AUDITORY EFFECTS

AUDITORY EFFECTS • Auditory fatigue- occur in 90 d. B and at 4000 Hz, associated with whistling & buzzing in the ear. • Deafness -, hearing loss, this is a serious pathological effect. The individual involved may not be aware at the early stage. Deafness may be temporary or permanent, in temporary, disability disappears 24 hrs after exposure to the noise, commonly occur at frequency range of 4000 - 6000 Hz, continuous exposure to noise at 100 d. B can result in permanent deafness. ( destruction of the organ of corti. Exposure to noise at 160 d. B may rupture the tympanic membrane & cause permanent deafness.

NON AUDITORY EFFECTS • Interference with speech- at 300 -500 Hz range • Annoyance- this is primarily a psychological response, neurotic people are more sensitive to sound. • Efficiency- where mental concentration is desired, noise may reduce work output. • Physiological changes- rise in Bp, rise in intracranial pressure, increase in heart rate, increase in breathing rate, increase in sweating, Giddiness, nausea & vomiting, sleeplessness, narrowing of pupils. • Economic losses- cost of noise induced hearing loss to industry is great

CONTROL OF NOISE Careful planning of cities Control of vehicles To improve the acoustic insulation of building Industries and railway must be situated away from residential areas • Protection of exposed persons through use of PPE • Legislation • Education • •

• THANKS FOR LISTENING

REFERENCES • Basavanthapa, B. T. , Community Health Nursing (2 nd edition). Jaypee brothers medical publishers , New Delhi • Park, K. (18 th ediition) Park’s textbook of preventive and social medicine. Banarsidas Bhanot Publishers, India.