Dr.Malik Muhammad Abdul Razzaq 1. Assistant Professor Department of Community Medicine Sheikh Zayed Medical College Rahim Yar Khan Dr.Malik Muhammad

Dr.Malik Muhammad Abdul Razzaq 1

Dr. Malik Muhammad Abdul RazzaqAssistant Professor

Department of Community Medicine Sheikh Zayed Medical College Rahim Yar Khan


Noise is often defined as “unwanted sound”, Noise is wrong sound in the wrong place, at the

wrong time. Noise has become a very important “stress

factor” Normal conversation produces a noise of 60-65

dB Whispering, 20-30 dB; Heavy street traffic 60-80 dB; Boiler factories about 120 dB; Normal tolerable limit is 85 dB;


Noise has two important properties:LoudnessLoudness depends upon the amplitude of the vibrations which initiated the noise. The loudness of noise is measured in decibels (dB).

Frequency:The frequency is denoted as Hertz (Hz.) One Hz is equal to one wave per second. The human ear can hear frequencies from about 20 to 20000 Hz. This range is reduced with age and other subjective factos. Many animals (e.g., dogs) can hear sounds inaudible to the human ear.


To signify the vast cacophony of sounds that are being produced in the modern life, are leading to health hazards.

These hazardous effects are:1. Auditory effects2. Non-Auditory effects


a. Auditory Fatigue: It appear in the 90 dB region and greatest

at 4000 Hz.b. Deafness:

The hearing loss may be temporary or permanent. Repeated or continuous exposure to noise around 100 decibels may result in a permanent hearing loss. c. Occupational hearing loss:

When there is exposure to noise above than 100 dB the result is hearing loss. Exposure to noise above 160 dB may rupture the tympanic membrane and cause permanent loss of hearing.


Interference with speech Annoyance Efficiency Physiological changes Economic loss


CAREFUL PLANNING OF CITIES CONTROL OF VEHICLES BUILDING ACOUSTIC INSULATION INDUSTRIES AND RAILWAYS PROTECTION OF EXPOSED PERSON

BY USING EAR PLUGS, etc. LEGISLATION EDUCATION


RADIATIONRadiation is part of man’s environment.

SOURCES: The sources of radiation are man – made and

natural Natural Man – Made 1. Cosmic rays 1. Medical and

dental X-rays, Radioisotopes 2. Environmental: 2. Occupational

exposure a. Terrestrial 3. Nuclear: b. Atmospheric radioactive fallout 3. Internal: 4. Miscellaneous:

Potassium-40 Television sets Carbon – 14 radioactive dial Watches, Isotope

tagged products,Luminous markers.


1. IONIZING RADIATION: Is applied to radiation which has the ability

to penetrate tissues and deposit its energy within them. Ionizing radiation may be divided in to two groups:

Electromagnetic radiations e.g., X- rays and gamma rays,

Corpuscular radiations e.g., alpha particles and beta particles (electrons) and protons.

Cosmic rays also contain ionizing radiations


These are electromagnetic radiations of wavelength longer than those of ionizing radiation. All non-ionizing form of radiations have less energy than cosmic, gamma, and X-radiation.


Roentgen:Roentgen is the unit of exposure. It is now replaced by Coulomb per kilogram

Rad:Is the unit of absorbed dose. It is now replaced by SI units as Gray

Rem:Is the product of the absorbed dose and the modifying factors. The Rem indicates the degree of potential danger to health.


1. SOMATIC EFFEXTS A dose of 400 to 500 roentgens on the whole body

is fatal. Immediate effects: Radiation sickness Acute radiation syndrome Delayed effects: i. Leukemia ii. Carcinogenesis iii.Foetal developmental abnormalities iv. Shortening of life2. GENETIC Chromosome mutations Point mutations


1. Avoiding Exposure to X-ray:Of the man – made sources, a dose of 4 rad is delivered a part of body when exposed to X-ray in about one minute. So unnecessary X-ray examination should be avoided in children and pregnant women.

2. Lead aprons:.5mm of lead apron will reduce the intensity of scattered X-ray over 90 per cent. Workers must wear a film badge or dosimeter which shows accumulated exposure to radiation.

3. Safe operation of nuclear power plants and enunciating the basic principles of radiation protection.



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Dr.Malik Muhammad Abdul Razzaq 1. Assistant Professor Department of Community Medicine Sheikh Zayed Medical College Rahim Yar Khan Dr.Malik Muhammad