physical factors iii. - univerzita karlova · october 10, 2016 ... indirect –excretion analysis...

Physical Factors III.Ing. Anna Schlenker

schlenker.anna@gmail.com

Physical Factors

October 10, 2016

Physical Factors – Noise, Vibrations

November 21, 2016

Physical factors – Non-ionising Radiation, Lasers

November 28, 2016

Physical factors – Ionising Radiation, Thermal comfort

Distribution of physical factors

A. Waves

1) Mechanical waves

a) noise - periodic changes of pressure in air layers

b) vibrations - oscillatory motion of an elastic environment about a fixed

point

Distribution of physical factors

2) Electromagnetic waves

a) non ionising radiation – lower frequency range

• radio waves (broadcasting, television)

• microwaves (generators, warming ovens)

• radar waves (radio locators)

• infrared radiation (thermal radiation)

• visible light (red - violet)

• ultraviolet radiation (A, B, C)

b) ionising radiation (alpha, beta, gamma, X-rays) – high frequency range

Electromagnetic Spectrum

„Spectre“ od Tatoute and Phrood – neznámý. Licencováno pod CC BY-SA 3.0 via Wikimedia Commons -http://commons.wikimedia.org/wiki/File:Spectre.svg#/media/File:Spectre.svg

Distribution of physical factors

B. Thermal Comfort

Environmental factors

1) Air temperature

2) Air humidity

3) Speed of air flow

4) Intensity of heat radiation

Individual factors

1) Activity

2) Thermal resistance of clothes

Ionising RadiationPhysical substance

Main sources of ionising radiation exposure in peace

1) Nature background

2) Medical exposure (X-ray examination, radio-therapy)

3) Nuclear energetics and liquidation of radio-active waste

4) Mining of radio-nuclides

5) Objects of common consumption (very old TV and computer tubes, some

phosphorescent materials)

Ionising RadiationCommon principles of health protection

1) Principle of justification – activity involving irradiation must be justified

(indication)

2) Principle of optimalization – the radiation must be as low as reasonably

attainable

3) Principle of non-exceeding the limits

4) Principle of source protection – physical protection of the source against

misuse by other person, and safeguarding its technical safety.

Ionising RadiationMethods of optimisation X-ray diagnostic and therapy

Technical arrangement

Limitation of entry field, shielding of non-irradiation body parts

Sufficient sensibly film materials and correct combination with folio make shorter exposure time, today also computer transmission without film use

Limitation of skiascopic examinations

Organisational arrangement

Good record-keeping of X-ray examination

Good access to X-ray medical report

Collaboration radiologists from different wards in hospitals

High caution by examinations of sexual organs

Ionising RadiationTypes of radio-nuclides

Sealed source of ionising radiation

A type of radio-nuclide, whose arrangement eliminate a possibility of elusion

of radioactive materials for anticipated conditions

cobalt bomb (complete arrangement)

Opened radio-nuclide

A type of radio-nuclide, which don’t answer to qualification of a sealed

source of ionizing radiation

Various radioisotopes (radiopharmaceutical materials)

Ionising RadiationBasic quantities in ionising radiation problems

Absorbed dose (D)

Energy absorbed per unit mass.

Its unit is the joule per kilogram, which is given a special name Gray: (Gy = J/kg)

Equivalent dose (H)

Absorbed dose (D) correct by special factor according to relative biological

effectiveness of radiation.

The unit is also joule per kilogram, with a special name Sievert: (Sv = J/kg)

Activity

Mean number of radioactive decays per unit time.

The unit s-1 has a special denotation Becquerel: (1Bq = s-1)

Ionising RadiationPrinciples of protection

Against (ionising) radiation

1) Distance – with square of distance is lowering absorbed energy of radiation

2) Shielding – materials containing lead, plasters with barium carbonate

3) Time – shorten of exposure time

Against radioactivity contamination (Opened radio-nuclides)

1) Work with liquid substances, no with powder materials (danger of inhaling or

spilling)

2) Work in small space – protection box, fume chamber

3) Work with a minimum necessary quantity of substance

Ionising RadiationMonitoring and prevention

(Radio) Active patient

A patient, which received radio-nuclide mostly in diagnostically order

Individual monitoring of persons in external irradiation risk

1) Personal dosimeter

2) Finger thermo-luminous dosimeter (work in protection box)

Individual monitoring of persons in inner contamination risk

1) Direct – External measuring by whole-body computer

2) Indirect – Excretion analysis (blood picture, haemato-crite, chromosomal

aberrations of lymphocytes, immunological indicators)

Ionising RadiationHealth contra-indications to work in external

irradiation risk

1) Pregnancy or lactation

2) Age lower than 18 years

3) Blood diseases and bleed diseases

4) Skin carcinomas and skin pre-carcinomas

5) Ovarian insufficiency

6) Vascular disorders

7) Organic disorders of nervous apparatus

8) More serious neurosis

9) Blood pressure exceeded normal limits

10)Skin disorders

11)Cataract

Thermal ComfortFactors determining temperature comfort of humans

Environmental factors

1) Air temperature

2) Air humidity

3) Speed of air flow

4) Intensity of heat radiation

Thermal ComfortFactors determining temperature comfort of humans

Individual factors - objective

1) Activity - transformation of chemical energy to thermal energy

2) Clothing insulation between an organism and environment - thermal

resistance of clothes

Individual factors - subjective

1) Adaptation and thermoregulation mechanisms (sensitive - resistant)

2) Health state (healthy - sick)

3) Mental conditions (comfort - stress)

4) Conditions of an organism (sleepy, rest, exhausted, satiety, hungry, etc.)

Thermal ComfortThermoregulation mechanisms of an organism

Convection - an exchange between warm air layers in clothes and

neighbouring cooler air

Conduction - take away of warmth to cooler areas

Heat radiation - infrared radiation

Evaporation - evaporation by perspiration from a body surface

Thermal ComfortMeasured quantities

Temperature

One of the important parameters to evaluate thermal comfort;

The recommended range for internal air temperature in apartment houses is

between 19 and 23 °C (grades of Celsius) in winter, and less than 27 °C

(grades of Celsius) in summer.

For temperature measuring we use any type of thermometers;

Thermal ComfortMeasured quantities

Air humidity

Absolute humidity - concentration of water vapours in air [g.m-3]

Relative humidity - a ratio between actual and maximum quantity of water

vapour by given temperature [%]

Thermal ComfortAir humidity

Hair hygrometer and thermohygrograf

Thermal ComfortAir humidity

Digital hygrometre and Psychrometer

Thermal ComfortAir humidity

The psychrometer compose of

a) normal thermometer

b) thermometer with a muslin sock, soaked in distilled water.

Both thermometers are aerated with a fan.

The air streaming from the fan evaporates water from the wet sock, and therefore

damp thermometer shows a lower temperature than the dry one.

The psychrometric difference is indirectly

proportional to the air humidity.

Thermal ComfortMeasured quantities

Air flow

Air flow in outdoor environment

(the wind) we measure by

different types of anemometers

Thermal ComfortAir flow

Low velocity random air movements

can be measured by Kata-thermometer

1) the cartridge we warm up in warm water

2) Then the cartridge fall is besides air temperature given also speed of air streaming.

3) The higher is a speed of air streaming the shorter is the time of cartridge fall.

Thermal ComfortMeasured quantities

Heat radiation

The principle of heat radiation is infrared energy exchange between a

human body and surrounding surfaces.

We find a serious radiate load in hot workplaces (glassworks, blast furnaces)

Thermal ComfortHeat Radiation

Heat radiation is measured by a

Globe thermometer. Globe

thermometer is a hollow metal globe

covered by a layer of polyurethane

foam, with a mercury thermometer

inside.

Its construction enables concentrate

IR radiation from surrounding areas

(walls, floor and ceiling).

Thermal ComfortMeasured quantities

Energy output

Net (clear) issue

measuring of heart activity (Holter apparatus)

orientation estimate: pulse rate, or spreadsheet method

A basal metabolism

an energetic value of basal metabolism depends on sex and falls with age (graphic finding)

Total (gross) energy output

nett (clear) energy issue + basal metabolism

Thermal ComfortMeasured quantities

Thermal resistance of clothes

Thermal resistance of clothes depends

on:

1) Number of clothes layers

2) Speed of air flow

The higher is the number of cloth layers,

the higher is number of thermal

insulation layers among these layers.

We can see a strongly decreasing of

protective ability of clothes against cold

by increase of air streaming speed.

Thermal ComfortEvaluation

Optimal thermal load - for apartment houses or for workplaces where only

moderately heavy work is performed. The table takes into consideration

winter and summer periods and combines all thermal comfort factors

except humidity. In these places humidity isn’t in most cases serious

problem.

Long-term feasible thermal load - for work places where heavier work is

performed (energy load, temperature). The graphs combine all thermal

comfort factors.

Short-term feasible thermal load - for work places with heaviest work (high

energy load, high temperature). They combine all thermal comfort factors.

They also include a time limit for non-interrupted work in such heavy

conditions.

Thank you for your attention!

Ing. Anna Schlenker

schlenker.anna@gmail.com