noise pollution

1. Dr. A R Rao
MD

3.  NOISE: “unwanted sound”.
 Wrong sound, in the wrong place, at the wrong
time.
 20th century: Century of noise.
 It has become an important stress factor.
 Noise pollution: cacophony of sounds that are
being produced in the modern life, leading to
health hazards.
 Automobiles, factories, industries, air-crafts,
railway junctions, bus terminals etc.
 Use of pressure horns, loudspeakers
 Domestic sources: transistors, radios, TV sets.

4.  Properties of noise:
1)Loudness or intensity,
2)Frequency.
 Loudness: amplitude of vibrations which initiated
the noise.
 Measured in decibels (dB).
 A daily exposure up to 85 dB is about the limit
people can tolerate with substantial ear damage.
 Acceptable noise levels:
Residential: 25-40 Commercial: 35-60
Industrial: 40-60 Educational: 30
Hospital wards: 20-35

5. Frequency: One hz is equal to one wave per
second.
 Range of human ears hearing frequency is 20 –
20,000 hz.
Sometimes noise is expressed in psycho-
acoustic terms – the Phon.
It considers intensity and frequency.

6. SOURCE OF SOUND LEVEL(dB)
WHISPER 10
SPEECH 2-3 PEOPLE 73
SPEECH ON RADIO 80
MUSIC ON RADIO 85
CHILDREN SHOUTING 79
CHILDREN CRYING 80
VACCUM CLEANER 76
PIANO 86
JET TAKE OFF 150

7. Basic instruments used in studies on noise:
Sound Level Meter: Measures Sound
Intensity.
Audiometer: measures The Hearing Ability.
Octave Band Frequency Analyser: measures
the noise in octave bands – “sound spectrum”

8. Effects of noise exposure:
1. Auditory,
2. Non-auditory.
1. Auditory Effects:
a. Auditory fatigue: appears at 90dB and
greatest at 4000hz, associated with side
effects – whistling and buzzing
b. Deafness:
a. Temporary (4000-6000 hz) – 24hrs
b. Permanent (100dB)
- noise above 160dB – rupture of tympanic
membrane

9. 2. Non-auditory effects:
a. Interference with speech: most disturbance to
300-500hz
b. Annoyance: irritation
c. Efficiency: mental concentration
d. Physiological Changes: rise in BP, heart rate,
breathing, intra cranial pressure and sweating,
interferes with sleep, nausea, giddiness and
fatigue, visual disturbance, affect colour
perception, reduce night vision
e. Economic loses

10. CONTROL OF NOISE:
1. Careful planning of cities,
2. Control of vehicles,
3. Improve acoustic insulation of building,
4. Industries and railways,
5. Protection of exposed persons,
6. Legislation,
7. Education.
Noise Pollution Control Rule 2000 under
Environment Protection Act 1996

12. RADIATION
•Radioactive contamination is the uncontrolled
distribution of radioactive material in a given
environment
•Contamination may occur from radioactive gases,
liquids or particles.
•Nuclear medicine, Nuclear fuel processing, Nuclear
explosion.
•Activity of radioactive material is measured in
Becquerel which is 1 disintegration per second.
This was earlier measured as Curies

13. NATURAL
1.Medical and dental: X-rays,
Radioisotopes
2.Occupational exposure
3.Nuclear: radioactive fall-
out
4.Miscellaneous:
1.Television sets,
2.Radioactive dials of
watches,
3.Isotope tagged
products,
4.Luminous markers.
Sources of RADIATION
MAN-MADE
1. Cosmic rays
2. Environmental:
a. Terrestrial
b. Atmospheric
3. Internal:
a. Potassium-40
b. Carbon-14

14. RADIATION
 Natural sources:
• Natural background radiation arises from three
sources
1. Cosmic rays: They originate in outer space &
are weakened as they pass through the
atmosphere.
• At ordinary living altitudes, their impact is
about 35 mrad a year.
• A commercial jet pilot receives about 300
mrad per year.

15. RADIATION
 Natural sources:
2. Environmental:
a. Terrestrial radiation: Radioactive elements
such as thorium, uranium, radium and an
isotope of potassium (K40) are present in
soil, rocks, buildings etc. – 50 mrad per year
b. Atmospheric radiation: The external
radiation dose from the radioactive gases
Radon and Thoron is about 2 mrad per year.
c. Internal radiation: These include minute
quantities of uranium, thorium, and related
substances, and isotopes of Potassium (K40),
Strontium (Sr90), and Carbon (C14)

16. RADIATION
2. Environmental:
a. Internal radiation:
Internal radiation is thought to inflict
about 25 mrad a year on the body as a
whole.
All in all, it is estimated that the total
natural radiation to which the average
person is subjected comes to
approximately 0.1 rad a year.

17. RADIATION
 Man-made sources:
1. X-rays: greatest man-made source of
radiation exposure to the general population
2. Radioactive fallout: Nuclear explosions
release a tremendous amount of energy in
the form of heat, light, ionizing radiation and
many radioactive substances, the important
being the isotopes of Carbon (C14), Iodine
(131), Cesium (Cs137) and Strontium (Sr90).
3. Miscellaneous: everyday appliances (e.g., TV
sets, luminous wrist watches) are
radioactive.

18. Types of Radiation
• “Ionizing radiation" is applied to radiation
which has the ability to penetrate tissues and
deposit its energy within them.
• Ionizing radiation may be divided into two
main groups :
• Electromagnetic radiations - X-rays and
gamma rays, and
• Corpuscular radiations - alpha particles,
beta particles (electrons) and protons

19. RADIATION
TYPE of
Radiation
Approximate penetrating ability
AIR TISSUE LEAD
Alpha
particles
4 cm 0.05 mm 0
Beta
particles
6-300 cm 0.06-4.0 mm 0.005 – 0.3
mm
Gamma rays 400 M 50 CM 40 MM
X-rays 120-240 M 15-30mcm 0.3 mm
Cosmic rays Very high for
some
components

20. RADIATION
•Alpha particles – 1- times as harmful as X-rays,
Beta & Gamma particles.
•Gamma rays & X-rays – short wave-lengths, deep
penetrating radiations
•X-rays – man-made,
•Gamma rays – spontaneously from radioactive
elements
•Cosmic rays – ionizing radiations

21. RADIATION
•Non-ionizing radiation – wavelengths longer
•Wavelength & energy inversely related
•These include
•Ultraviolet radiation,
•Visible light
•Infrared radiation
•Microwave radiation
•Radio-frequency radiation

22. Radiation units
•The activity of a radioactive material is the
number of nuclear disintegratons per unit of time.
•The unit of activity is a becquerel (Bq); 1 Bq is
equal to 1 disintegration per second.
•Formerly, the unit of activity was curie (Ci) and 1
1 Bq ~ 27 picocuries
•Potency of radiation
1. Roentgen - unit of exposure
2. Rad – unit of absorbed dose
3. Rem – product of absorbed dose &
modifying factors

23. Radiation units
•SI units of Radiation
•Coulomb per kilogram – 1 roentgen = 2.58
*10-4 C kg-1
•Gray (Gy) replaced Rad
•Sievert (Sv) –replaced Rem – 1 sievert = 100
rems
•1 Rad = 0.01 Gy
•Dose equivalent (H)
•H=DQ (D-absorbed dose, Q-quality factor)

24. Biological effects of Radiation
•Somatic effects: 400-500 roentgens – fatal
•25-30 – blood corpuscles
•Delayed effects are mainly of three kinds :
leukaemia, malignant tumours and shortening
of life.
•Genetic effects
•May manifest in the remote off spring

25. Biological effects of Radiation
Somatic
Immediate
Radiation
sickness
Ac. Radiation
syndrome
Delayed
Leukaemia
Carcinogenesis
Foetal dev
abnormalities
Shortening of
life

26. Radiation protection
•Protection
•Dose from man-made sources should not
exceed 5 rad a year.
•Unnecessary X-ray examinations should be
avoided, especially in the case of children and
pregnant women
•Proper use of lead shields and lead rubber
aprons (0.5 mm of lead) will reduce the
intensity of scattered X-rays over 90%
•Dosimeter
•Periodic medical examinations, regular
working hours. Recreation, and holidays

27. Radiation protection
•International Commission on Radiological
Protection (ICRP)
•International Atomic Energy Agency (IAEA) and
•World Health Organization (WHO)
•Recommend –
•Genetic dose- not to exceed 5 rems / 30
yearss