Basic Directions of Atmosphere Protection from Anthropogenic Pollution

v Administrative-legislative measures: Law of Ukraine on air protection, Constitution, Law on sanitary and epidemic well-being of population of Ukraine, and other laws.Theadministrative measures are taken by local authorities in the given territory.

v Hygienic measures include:

Ø Preventive sanitary control (see Topic 1)

Ø Current sanitary control

v Medical-preventive measures — studying the effect of pollution on health of population, treatment and improvement of victims, revealing the main negative factors, sources, etc.

v Ecological monitoring — studying the state of ecosystems and separate kinds of biota in interrelation with atmospheric pollution.

v Architectural measures — zoning of cities, sanitary-protective gaps between sources of pollution and residential buildings, etc.

v Technological measures include:

Ø Application of self-contained technologies — the air is purified and again returns in operation, thus there are no emissions in free air. It is a very expensive method.

Ø Change of technology — transfer of motor transport into usage of electricity, gas; change of chemical technologies with decreased concentration of harmful substances in emissions.

Ø Usage of sewage disposal plants in sources of pollution:

§ cyclone, multicyclone — a great rotary speed is imparted to emission and the particles drop out in the bunker;

§ scrubber — air passes through water and gases are purified;

§ electric filter — the charged particles are deleted.

Checking the work of sewage disposal plants is carried out by observing the specifications of MPE (maximal permissible emissions of pollutants in free air calculated in consideration of MPC in the air).

Recommendations for Practical Classes on the Topic

Key Questions:

1.Chemical structure of air and physiological significance of its basic components.

2.The reasons, manifestations and prevention of high-altitude (mountain) and caisson (decompression) sickness.

3.Significance of definition of СО2 in the air of premises. MPC of СО2 and its substantiation.

4.Basic sources and factors of atmosphere pollution, criteria and parameters (physical, chemical, bacteriological) of pollution of atmospheric air. Ways of autopurification of atmosphere.

5.Manifestations of atmosphere pollution effect on a human health and conditions of life.

6.Basic directions of atmosphere protection from pollution.

7.Hygienic significance of ventilation in different premises. Types of ventilation. Classification of ventilating devices.

8.Hygienic characteristics of ventilation efficiency and calculation of its parameters.

Learning Objectives and Their Concrete Definition

1. To determine efficiency of natural ventilation by CO2 content in the air of premises.

The method of СO2 estimation is based on comparison of pumped by a rubber syringe atmospheric air and air of a premise (one and the same volume of passing air is taken). In Petry’s absorber 10 ml of coloured by phenolphtalein solution of Na2CO3 is poured. While passing through the solution, the air with СO2 becomes colourless; its reaction with alkaline Na2CO3 to acidic Na2НCO3 varies. By pressing a rubber syringe, we slowly squeeze out air from it into absorber through a long tube, thus we fix the number of pumpings until a complete decolouration of the solution. The same procedure is carried out in the open air, the solution being substituted for a new one. The calculation is made according to the formula:

 

Х = A x 0.04 / B,

 

where: Х — the required content of СО2 in %

A — amount of pumpings in the atmosphere

B — amount of pumpings in a premise

0.04 %- an average concentration of carbon dioxide of the air.

We estimate concentration of carbon dioxide in a premise: the optimum concentration of CO2 is 0.07-0.08 %, MPC — 0.1 %.

2. Estimation of efficiency of natural ventilation and air changes per hour.

Air changes per hour as a parameter of efficiency of natural ventilation is defined by an indirect method proceeding from the received results of the СО2 content in a premise according to the formula:

 

where: N-number of people in a premise

V- cubic capacity of premise

Р- found concentration of СО2

22.6- volume of СО2 exhaled by a man per hour

0.4 (l\m3) — an average concentration of СО2 in the air

3. Estimation of parameters of artificial ventilation in situational tasks.

Example: Length of a premise makes up 22.4 m, width — 6m, height — 3.5 m. In the premise there is one vent 40 cm in diameter; the speed of air movement makes up 5 m/sec. Identify the air changes per hour and estimate it. Air changes per hour is a ratio of quantity of entering air per cubic capacity of a premise. The quantity of entering air per hour is identified by multiplying the vent area by speed of air movement and time of airing.

 

V- speed of air movement;

S- area of vent in m2,

N- number of vents

T — time of airing (1hour = 3600 sec)

Vp- cubic capacity of a premise (room) in m3

Solution: the area of the vent (since it is of a round form) is determined according to the formula O = π x R2n, i.e. =3.14х (0.2) 2 = 0.13 m2.

 

Air changes per hour is equal to 5, that exceeds the established standards.

Self-control Tests

1. In the structure of atmospheric air the maximal percentage makes up:

A. oxygen

*B. nitrogen

C. carbon dioxide

D. argon

E. neon

 

2. MPC of СО2 for various premises makes up

A. 0.07%

B. 1.1%

*С. 0.1%

D. 0.01%

E. 0.04%

 

3. What kinds of artificial ventilation do you know?

A. natural, artificial ventilation

*B. input ventilation

*C. extract ventilation

D. combined ventilation

 

4. At the expense of what factors is the natural ventilation carried out?

A. difference of air in a premise and outside

*B. difference of temperatures in a premise and outside and increased pressure of external air at wind

C. presence of sources of radiation temperature in a premise

D. difference of temperatures and humidity in a premise and outside

E. difference of speed of air movement in a premise and outside

Problem Solving

1. In a room 400 m3 in size there is a ventilating fan, which is switched on during a break between lectures for 10 min. Its vent is round with a radius of 0.2 m. Identify the air changes per hour, if the speed of air movement in the vent makes up 6 m/sec.

2. In a room with a cubic capacity of 60 m3 there are 5 men. Airing occurs at the expense of a window leaf, which is opened for 10 min per hour; speed of air movement is 1m/sec, area of the window leaf is 0.15 m2. Estimate the ventilation in the room.

3. Microclimate of a premise is characterized by the following parameters: the air temperature — 40oС; relative humidity — 70 %; speed of air movement — 0.1 m/sec; radiation temperature — 80-90oС. Identify the most probable pathological state of a person, which can occur under the given microclimatic conditions.

Standard Answers:

1. According to the formula ACh = VxSxNxT/Vp we find out: 6 х [3.14х (0.2)2] х1х600 =1.113 / Vp 400.

ACh = 1, that is not enough for the given room (N=3)

2. Per 1 sec. 1 х 0.15 = 0.15 m3 of air enters the room; for 10 minutes — 90 m3. ACh is equal to 90 m3: 60 m3 =1.5. The necessary air changes per hour are 22.6 х 5/1-0.4=188 m3. The necessary air changes per hour are 188 m3: 60 m3 = 3. The necessary air changes per hour are 3 times/hour.

3. General hyperthermia (heat stroke).

 

Fig. 19. Aspirator (device for aspiration of air for detecting pollutants in the air)

 

In aspirator the system of regulation is on a forward panel of the device: 1 — for connection of a cord to the electricity supply with voltage of 220 V (at 127 V a transformer is applied); 2 — toggle for switching on and switching off the device; 3 — handle of rotameter valves for regulating speed of taking air samples; 4 — rotameters; 5 — connecting pipes for connection rubber tubes with filters; 6 — safety valve serving for prevention of the electric motor lugging at taking samples with small speeds; 7 — socket of a safety-lock; 8 — a bonding point of device.

Starting the work, it is necessary to ground the device, attaching plug 8 to water pipe or heating system with the help of a flexible wire, and then it is connected to electricity supply. Then the safety valve 6 is fixed in position 1 and valves of rotameters 3 are opened to the full. After that the device is switched on by toggle 2 and by rotating handles of rotameter valves the necessary speed of taking air samples is established. Then the device is switched off, the necessary absorbers for taking samples are attached to connecting pipes 5 and the device is switched on again, noting the time by a stop watch; by rotameter the necessary speed of air passage is established and samples are taken. Readout of air speed is carried out from the top edge of floats of rotameters. Aspirator is designed for continuous work within 3 hours.

 

Theme No 6.

Significance of Solar Radiation. Hygienic Requirements to Lighting

Hygienic Significance of Solar Radiation

All the organic life on Earth owes its existence to the Sun energy — the only external source of heat and light.

On the border of atmosphere the intensity of solar radiation is on average 2 cal/cm2/min, it is called a “solar constant” (it depends on activity of the Sun and other astronomical factors).

Due to absorption, dispersion and reflection of solar beams the quantitative and qualitative changes of solar radiation take place in atmosphere:

· Quantitative changes — only 43 % of solar constant reach the Earth surface (it depends on geographical position, height of the Sun above the horizon, clearness of atmosphere).

· Qualitative changes in spectrum of solar radiation are as follows:

On the border of atmosphere the ultraviolet beams (UV) make up 5 %, visible beams — 52 %, infrared beams (IR) — 43 %, near the Earth surface UV — 1 %, visible beams — 40 %, IR — 59 %.

The reason of these changes is 2 screens:

· the electro-magnetic field of the Earth,

· an ozone layer, due to which deviation of short-wave beams and delay of long-wave part of solar radiation take place.

Reasons, Manifestations and Prevention of Solar Starvation

At lack of solar irradiation a peculiar pathological condition develops in people — solar starvation, which is characterized by asthenovegetative syndrome, oppression of CNS, decrease of adaptable abilities of organism. In children rickets may develop. The main reason of development of this condition is deficiency of UVR.

The reasons of development of solar starvation are the following:

· Insufficient stay in the open air. There is lack of solar irradiation in rooms, because window glass reflects 35-90% of solar beams.

· Climatic and geographical conditions of region, e.g. in the Far North where the polar night lasts 6 months and there is no Sun, and the weather is very cold, children cannot stay in the open air.

· In Europe the lack of solar irradiation is experienced by the rural population for 2 months a year, and by urban population — 4 months/year (due to high level of air pollution).

· Pollution of atmosphere which results in reduction of light exposure by 40-50 %, especially of UVR. Thus in the center of London the level of UVR is 36 times lower than in its suburbs.

· Occupational hazards, e.g. in miners, submariners, etc.

Prevention of solar starvation includes the following measures:

· The increase of staying in the open air: a correct regimen for children is of great importance.

· A correct planning of residential areas and buildings (distance from each other), the observance of norms of natural lighting in premises.

· Struggle against atmosphere pollution.

The most effective way of solar starvation prevention is using preventive UVR in special photaria with luminescent UV lamps in mines, in the Far North, at home for children in the periods of possible solar starvation.

Before administering the course of UV radiation it is necessary to determine a biodose of UVR for each concrete person, because it is different for everybody.

 

Biodose of UVR and Its Definition

It is the minimal time of UVR causing a small erythema on not sunburnt skin (reddening of skin) in 8-20 hours after UV irradiation. The minimal daily preventive dose of UVR is 1/8 part of biodose, the optimal dose (treatment of rickets) is 1/2-1/4 of biodose.

Effect of Separate Components of Solar Radiation on Organism

Table 32

SPECTRAL DISTRIBUTION AND BIOLOGICAL ACTIVITY OF SOLAR RADIATION

Kind of radiation	Wave length	Mechanism	Biological effect
Infrared	20000 – 760	Thermal	Heating tissues, intensifying metabolism
Visual	760 – 400	Thermal, weak photochemical	Sensation of light, irritation of CNS
Ultraviolet:	400 – 180	Photochemical	Formation of melanin; Bactericidal, erythemic effect; Synthesis of vitamin D in the skin; Fluorescent effect
Range A	400 – 315
Range B	315-280
Range C	280 – 180
Range D	285 – 265

Ultraviolet (UV) Ray

The most biologically important part of solar spectrum is UV-rays. The length of a wave is 10-400 nanometers. The mechanism of action is a photochemical effect: on their entry into the skin the biologically active substances are formed (histamine, choline, acetylcholine, etc.) causing photochemical erythema of the skin (its signs are precise borders, then melanin formation).

Types of biological effect of UVR are as follows:

· getting sunburn (melanin formation), fluorescent at UVR effect in area A (the length of wave is 400-315 nm)

· erythematous, bactericidal — area B (315-280 nm)

· luminescent with increasing the previous effects — area C (280-20 nm)

· antirachitic — area D (285-265 nm).

In optimal doses UV produces a common strengthening effect, stimulates growth and regeneration of tissues, improves metabolism and functions of endocrine and immune systems.

Overdosage of UVR (a sharp effect) causes photoerythema, dermatites, burns, increase of body temperature, photoelectric ophthalmia.

A chronic effect of big UVR doses results in deterioration of health state, decrease of capacity for work, aggravation of chronic diseases; it is a risk factor of skin cancer — in southern areas skin melanomas in population are 4-5 times more frequent than in the Northern areas.

Visible Light

The length of wave is 400-760 nm; it has a slight photochemical effect — a photosensibilization action on optic nerves in retina. There is also a slight thermal effect — inhibition of light quanta in tissues.

It stimulates the CNS through excitation of the visual center, has a positive effect on emotional state of the man, function of cardiovascular system and other systems.

At excessive intensity it may have a blinding effect down to destruction of photosensitive elements and development of retinitis — inflammation of retina.

Infrared Rays (IR)

The length of wave is more than 760 nm. Their main effect is thermal — increase of oscillatory and rotational movements of molecules in tissues. They intensify the biological effects of UVR.Two parts in infrared rays are distinguished:

· long-wave infrared rays — more than 1500 nm;

· short-wave infrared rays — 760-1500 nm.

Biological effects of infrared rays are the following: hyperemia of skin and internal organs, increase of gas exchange in tissues, strengthening of secretory function of kidneys, analgesic effect, elimination of inflammatory foci. They are widely applied in physiotherapy.

At excessive intensity of infrared irradiation the following may occur:

· heating of brain membranes causing heatstroke and fainting,

· damage of crystalline lens by short-wave IR-rays leading to cataract

· burns on skin of different degree of severity.

Hygienic Requirements to Natural Lighting (Illumination)

At estimation of natural lighting in premises the following should be taken into account:

· Orientation of windows according to the compass points;

· Distance to the neighbouring buildings, plants (in norm distance between buildings should make up 1.5 of their height, trees should be not closer than 10 m to buildings, schools;

· Size, number, form of windows in a premise; % of window sashes should make up 25 % of window area;

· Availability of extraneous objects on windows. Curtains, green plants, etc. are not recommended in schools.

Then the quantitative parameters are estimated including:

· Light coefficient (LC) — the ratio of the total area of windows in a room to the area of the floor. The LC in habitable rooms should be 1/8-1/10, in hospital wards and consulting rooms of doctors — 1/5-1/6, in school classrooms — 1/4-1/5, in operating rooms — 1/2-1/4.

· CNI — coefficient of natural illumination — the ratio of illumination in workplace in Lux (by luxmeter) to light exposure in the open air in Lux, expressed in %. The normal CNIfor habitable rooms makes up 0.5-0.75 %, for wards — 1 %, classrooms — 1.5 %, operating rooms — 1.6-2%.

· Light angle — not less than 27 degrees.

· Ventiduct angle — not less than 5 degrees.

 

Luxmeter (the device for estimation of illumination) (Fig. 20).

A perceiving part of the device is a photocell transforming light energy into electrical one. A recording part is a sensitive galvanometer graded just in lux. The received results are compared with the established norms.

If the evaluation is made in the daytime, at first it is necessary to identify the illumination created by mixed illumination (natural and artificial), and then after switching off the artificial illumination. The disparity between the received data will make up the value of illumination created by artificial illumination.

 

Fig. 20. Luxmeter

 

Hygienic Requirements to Artificial Illumination

The common requirements to artificial illumination are as follows:

· It should be sufficient by level of illumination,

· It should approximate by spectrum to natural light,

· It should be uniform in space not to create sharp contrasts in illumination, otherwise tiredness occurs faster because of light adaptation,

· It should be uniform in time,

· It should not blind organs of vision.

The main parameter of sufficiency of artificial illumination is illuminance of surfaces in lux. It is measured by luxmeter with the help of photocell.

Systems of artificial illumination are the following:

· Common — in a habitable room — 40-50 lux, classroom — 150 lux, operating room — 300 lux (this is the norm for incandescent electric lamps, for luminescent lamps it is 2 times more);

· Local — in a habitable room — 100 lux, classroom — absent, operating room — 3,000-10,000 lux,

· Mixed — local and common illumination together.

The Hygienic Characteristics of Sources of Artificial Illumination

· Candles, oil-stoves, etc. are characterized by nonuniform illumination in time, air pollution in premises;

· Incandescent electric lamps — their spectrum differs from natural light (there are a lot of red beams);

· Luminescent lamps are characterized by non-uniformity in time, differences in spectrum (there are a lot of blue beams).

 

 

Types of Lighting Fixtures

· Lamps of direct light have high contrasts in illumination resulting in blinding eyes

· Lamps of reflected light requiring a more powerful light source

· Lamps of diffused light (frosted glass spheres) are best of all.

Recommendations for Practical Classes on the Theme

Key Questions

1.Significance of solar radiation, the spectral structure of solar light.

2.Concept of solar starvation, reasons, manifestations and prevention.

3.Physiological effect of various components of a solar spectrum: UV, visible beams, IR–rays.

4.The basic sanitary-hygienic requirements to illumination.

5.Characteristics of light units.

6.Principles of estimation of natural and artificial illumination.

7.Hygienic estimation of natural illumination of premises.

8.Hygienic characteristics of systems and types of artificial illumination.

9.Hygienic requirements to illumination of habitable premises and classrooms.

10.Hygienic requirements to illumination of hospital wards.

11.Hygienic requirements to illumination of operating rooms.