Transcript noise - Dr Muhammad Razaq Malik

Dr. Muhammad Razzaq Malik
Assistant Professor
Department of Community Medicine,
Sheikh Zayed Medical College,
Rahim Yar Khan
NOISE
NOISE
• 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;
PROPERTIES
• Noise has two important properties:
Loudness
Loudness 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.
NOISE POLLUTION
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 effects
2. Non-Auditory effects
AUDITORY EFFECTS OF NOISE
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.
NON- AUDITORY EFFECTS
•
•
•
•
•
Interference with speech
Annoyance
Efficiency
Physiological changes
Economic loss
CONTROL OF NOISE
•
•
•
•
•
CAREFUL PLANNING OF CITIES
CONTROL OF VEHICLES
BUILDING ACOUSTIC INSULATION
INDUSTRIES AND RAILWAYS
PROTECTION OF EXPOSED PERSON BY
USING EAR PLUGS, etc.
• LEGISLATION
• EDUCATION
RADIATION
• RADIATION
Radiation 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 Xrays, Radioisotopes
• 2. Environmental:
2. Occupational exposure
•
a. Terrestrial
3. Nuclear:
•
b. Atmospheric
radioactive fallout
• 3. Internal:
4. Miscellaneous:
• Potassium-40
• Carbon – 14
•
Television sets
radioactive dial
Watches, Isotope tagged
products,
Luminous markers.
TYPES OF RADIATIONS
• 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
NON – 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.
RADIATION UNITS
• 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.
BIOLOGICAL EFFECTS OF RADIATION
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 life
2. GENETIC
• Chromosome mutations
• Point mutations
RADIATION PROTECTION
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.
THANK YOU