Экологическая медицина = Ecological medicine. Учебное пособие

When locating and designing residential buildings, the degree of radionuclide hazard and the possibility of technogenic radioactive contamination in the built-up area must be taken into account.

Architectural-planning and constructive solutions for blocks of flats and premises should comply with the requirements of current SNB 3.02.04–03 “Residential Buildings”.

The re-profiling of a part of a residential building or its use for other purposes is allowed with the decision of the local executive and administrative authorities to withdraw these rooms from the living premises and only with the consent of the state sanitary inspection authorities and institutions in accordance with the requirements of the sanitary rules and norms in force. Residential buildings must include measures to ensure wheelchair access and living conditions.

Reconstruction and repair of blocks of flats and premises require, in accordance with the specific conditions, the provision of landscaping, equipment for cold and hot water systems, sewerage and drainage, heating, electricity, garbage chutes, lifts, and other necessary engineering communications.

It is forbidden to place objects of industrial activity, trade, cultural and mass work, sports facilities, consumer service businesses, medical and preventive organisations in residential buildings. This can release elevated concentrations of harmful substances into the air environment of residential premises and atmospheric air. In addition to creating excesses of permissible levels of radiation, noise, and vibration, these sources also adversely impact the microclimate and other indicators of indoor environment quality, living conditions, and contribute to the spread of infectious diseases.

The main hygienic norm for dormitories: the area of bedrooms per person is not less than 6 m2, the height is not less than 2.7 m. Additionally, in dormitories designed for more than 300 people, a catering canteen, a pharmacy and a medical centre are provided.

Residential buildings and premises should, as a rule, be equipped with cold and hot water supply, sewerage, heating, ventilation with natural air circulation, electricity, gas supply. Natural ventilation of residential and auxiliary premises must be carried out through vents, transoms, special shutters, ventilation ducts. Exhaust vents of ventilation ducts are arranged in sanitary units (bath, toilet) and kitchens.

The heating and ventilation system in the construction of buildings must ensure hygienic standards for air quality, noise and vibration levels, as well as the microclimate in residential premises (Table 7.2).

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Table 7.2. Indicators of optimum microclimate in living premises

Permissible microclimate parameters in residential premises during the heating period:

yyair temperature is +18 °C; yyrelative humidity is 30%–65%;

yyair velocity is no more than 0.25 m/sec.;

yytemperature difference between the air temperature of the premises and the walls is no more than 6 °C;

yytemperature difference between the indoor air temperature and the floor temperature is no more than 2 °C.

Architectural and planning solutions for the dwelling should provide a comfortable indoor environment, i.e., a favourable microclimate and adequate natural illumination. The heating system should provide uniform air heating during the entire heating period, be easy to operate and regulate. In the residential premises water heating is used, which provides uniform heating of the air by convection at the radiator temperature not exceeding 700 °C. Panel heating relies on radiant heat transfer. The heating device is a panel (wall), the ceiling or the floor of the room. The most favourable temperature range is 40–45 °C for the wall panels, 28–30 °C for the ceiling, and 25–27 °C for the floor. Air exchange frequency should be 1–1.5 per hour. A modern flat has a combination ventilation system, e.g., artificial exhaust ventilation in the kitchen and sanitary unit, and supply ventilation in the living areas.

The concentration of harmful substances and contaminants in the air of residential premises should not exceed the level of concern (LOC) for pollutants in the atmospheric air of populated areas. The levels of noise,

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infrasound, vibration, ionising radiation and electromagnetic fields from internal and external sources in the living quarters and the surrounding area should not exceed the values established by the current sanitary rules and standards.

Natural light is determined by the orientation of the building, the number of floors, the size of windows, the presence of balconies, etc. The daylight factor is 0.5%, the light factor for living rooms is 1:8. The greatest hygienic value is insolation. Continuous insolation in northern areas should be at least 3 hours, in summer in central areas – at least 2.5 hours.

Artificial lighting should correspond to the purpose of the premises, be sufficient, adjustable and safe, not have a blinding effect and other adverse effects on the person and the internal environment of the premises. The average illumination of living rooms in flats and dormitories, with the combined effect of all lamps must be 75 lux, and in the kitchen of flats and dormitories – up to 100 lux, sanitary units – 30 lux.

Commissioning of blocks of flats and premises completed, reconstructed, after major repairs, including individual engineering networks of residential buildings (water supply, sewerage, heating, ventilation), without the conclusion of the territorial authorities and institutions of state sanitary and epidemiological supervision is not allowed. The commissioning of completed blocks of flats and premises or a separate step-by-step commissioning of engineering networks is permitted after positive results of instrumental and laboratory tests, including the quality of drinking water, physical factors (if there are sources inside the building), and the microclimate, if necessary.

Laboratory and instrumental studies prior to commissioning completed construction, reconstruction and capital repairs of blocks of flats and premises, as well as during their current operation, are provided by enterprises, organisations, institutions and private individuals under whose jurisdiction the housing stock is located.

Characteristics of indoor air environment factors affecting human health.

The most powerful pollutant in enclosed spaces is tobacco smoke. The process of tobacco combustion produces about 600 different chemical compounds, which can have carcinogenic, toxic, allergenic, and other effects. They include carbon monoxide, nitrosamines, aldehydes, nicotine, benz(a)pyrene, acrolein and others. Smoking causes 3 million deaths worldwide annually. When tobacco is burned, the air is polluted due to two mechanisms – primary and indirect. Combustion products are consumed through tobacco smoke inhalation. The indirect source of air pollution is

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the smouldering process of the cigarette, which lasts 8–10 minutes. Tobacco smoke is hazardous for active and passive smokers. Passive smoking is especially dangerous for children, as they are more sensitive to tobacco smoke effects.

Natural gas and combustion product. Gas is a multi-component system consisting of dozens of different compounds. Natural gas in the house is a source of many different pollutants. Among them are odorants – gaseous hydrocarbons, poisonous organometallic and radioactive radon, which are directly present in the gas; products of incomplete combustion (carbon monoxide, nitrogen dioxide, aerosol organic particles, polycyclic aromatic hydrocarbons). All of them can work both separately and in combination with each other, producing a synergistic effect. Odorants are sul- phur-containing organic aromatic compounds (mercaptans, thioethers, etc.). They are toxic and irritate the eyes and skin. Combustion of gas creates aerosols containing carcinogenic organic compounds, and some volatile organic compounds, including formaldehyde. These components can cause allergies.

Biological factors that pollute the indoor air environment include house dust mites, which allergenise.

In institutions, when copying equipment is used, there is an accumulation of ozone. Monitor enclosures made from plastic can release triphenyl phosphate, an organophosphorus compound that can cause allergic reactions when inhaled. Human well-being is also affected by aeroions. In poorly ventilated rooms, the content of positive aeroions increases and is one of the causes of “sick building syndrome”. The most common symptoms associated with this syndrome are drowsiness, stuffy nose, dry throat, headaches, irritated and dry eyes, and other non-specific reactions.

At present, the energy saturation of residential premises, houses, offices has increased due to the use of electrical appliances, which are sources of electric and magnetic fields. The whole set of electromagnetic fields is called electrosmog. Electromagnetic pollution is a condition in which the population is exposed to a low-frequency (LF) and medium-frequency (MF) electromagnetic field (EMF) exceeding sanitary standards.

External sources of LF and MF EMFs are sources of LF and MF EMFs located in the residential area. They adversely affect the health of the population in this area if they exceed the levels permitted by sanitary standards.

Internal sources of LF and MF EMFs are sources of LF and MF (certain types of consumer goods) EMFs, located directly in residential areas or adjacent premises, which have an adverse effect on the health of the

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population living in them in case of exceeding the levels permitted by the sanitary standards.

Conditions of LF and MF EMF influence on the population can be: yycontinuous and intermittent;

yygeneral and local;

yycombined from multiple sources;

yycombined with other adverse factors of the living environment. The results of prolonged exposure to LF EMF are:

yyirritability, impatience, fussiness, impaired attention, memory and sleep, increased fatigue;

yytension of the immunity humoral link, as well as unbalanced immunity mechanisms;

yychanges in brain bioelectrical activity; yydecreased psyche adaptation reserves;

yydeterioration of a person’s psychophysiological state; yychanges in vegetative functions;

yydecreased fertilisation function in men; yyvascular changes in the retina; yypossibility of leukaemia development.

Specific features of exposure to MF EMF on the human body are: yyincreased fatigue, impaired attention, memory and sleep, irritability; yyasthenic syndrome;

yyastheno-vegetative syndrome; yyhypothalamic syndrome; yyexacerbation of chronic diseases;

yyaggravation of general diseases (blood diseases, hypertonic disease, etc.). The most sensitive human systems to LF and MF EMF are:

yynervous (change in haematoencephalic barrier function, influence of EMF on glial brain tissue, on neuronal membranes, on memory, on con- ditionally-reflexive activity);

yyimmune (decrease in phagocytic function of neutrophils, changes in complementary activity of blood serum, development of autoimmunity); yyendocrine (changes in the hypothalamic-pituitary-adrenal system); yysexual (degeneration, pyknosis of cellular elements of the spermatogenic epithelium, changes in the ratio of cellular forms, cytochemical

shifts, hormonal disorders).

The measurement unit of the electric field component of the LF and MF range is the voltage per unit length, i.e., volts divided by one metre (V/m) or kilovolts per metre (kV/m), respectively.

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The measurement unit of the magnetic field component of the LF and MF range is the voltage per unit length, i.e., ampere divided by metre (A/m) and the magnetic induction is microtesla (μT) or nanotesla (nT), respectively.

Sources of LF EMF:

External:

1.  Power lines of different voltages. The source of energy radiation (electromagnetic energy of the field of industrial frequency of 50 Hz) into the surrounding space are wires.

The intensity of fields under the line depends on the voltage class (electric field), load (magnetic field), height of suspension, distance between the wires, vegetation cover of the terrain under the line. Levels of intensity of electric field current of industrial frequency in buildings reach 1.2– 182 V/m depending on the distance, which is much lower than the permissible level (on the territory around the residential area – 1,000 V/m; within residential areas – 500 V/m) and does not lead to a significant increase in electromagnetic burden on the population. Magnetic induction reaches 250–560 nT at the buildings, exceeding the recommended safe level of 200 nT (Sweden). Living near power lines exposes people to electromagnetic fields (EMFs) 24 hours a day, which is why the magnetic field load, exceeding the recommended level 1.2–2.3 times, is significant.

Zones of adverse effect of power lines on the population can be from 20 to 200 m and more on both sides of the outermost wires (mainly due to the magnetic component of the field).

2.  Transformer and power substations, electric power plants, open switchgears, electrical installations – these sources are significantly (250– 1,000 m) distant from residential buildings and areas of residential buildings in cities and settlements. They form an electric field strength equal to 1.0–3.0 V/m and magnetic induction levels 40–80 nT which is considerably lower than the fixed normative values of the electric field component (500 and 1,000 V/m) and the recommended levels of the magnetic field component (200 nT, Sweden). In this regard, they do not have a significant impact on the electromagnetic background of these territories.

Internal sources: power cables, cable lines, power distribution points in residential buildings. Persons living in rooms adjacent to these sources are exposed to high levels of LF EMF. Maximum values of electric field strength 180–280 V/m (MPL 500 V/m) and magnetic induction field strength 800–2,600 nT are registered just by the wall, behind which the source of LF EMF is located. The greatest contribution is made by the

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common power cable (2,600 nT), electric power distribution point (1,600 nT) and cable line (800 nT). Electric field strength levels registered in flats from these sources do not exceed the permissible level of 500 V/m, while the safe level (0.2 μT, Sweden) of the magnetic component of the field in flats from power cables, cable lines and power supply distribution points is reached at a distance of 3.0–3.5 meters from the source. As a result, people living in rooms adjacent to these sources are exposed to high levels of magnetic induction (4–13 times higher than the recommended safe level of Sweden) around the clock; electrical appliances – depending on the operating time during the day.

These sources are divided into 3 groups:

1)  products designed for 24–hour operation – refrigerators, freezers, ventilation fans, air conditioners, etc.;

2)  products designed for long-term operation (from 1 to 6 hours a day) – washing and sewing machines, air cleaners for kitchens, PCs, video and audio equipment, televisions, etc.;

3)  products designed for short-term operation (less than 1 h per day) – vacuum cleaners, microwave ovens, meat grinders, mixers, coffee mills, irons, hair dryers, etc.

The overall level of electromagnetic pollution in residential areas is affected by the operation of contact (mixer, iron, hair dryer, electric shaver, electric drill, etc.) and non-contact (refrigerator, washing machine, TV, microwave oven, radio, kettle, toaster, etc.) electrical household products. Levels of electric field intensity at the surface of these products are from 160 V/m to 420 V/m, not exceeding the hygienic standard of 500 V/m. The levels of magnetic induction of the same products reach 0.12–11.6 μT, which indicates that the safe level (0.2 μT, Sweden) of the products is exceeded 2–58 times. The recommended safe level for humans 0.2 μT is reached at distances from 0.8 to 1.0 metres from the product.

The most unfavourable magnetic field levels are microwave oven, electric stove, electric heater, freezer, vacuum cleaner, refrigerator, fluorescent lamp (1.8–11.6 μT).

Thus, electrical household products are a significant source of LF EMF, which has an adverse effect on human health.

The prevention basis against adverse effects of LF and MF range electromagnetic radiations on the health of the population is to ensure compliance with hygienic regulations of this factor in the residential area and in living quarters. The basis is achieved by three main areas of activity:

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yycombating electromagnetic radiation of the LF and MF range at the source of their formation (implementation of modern technologies in the production, transmission, and distribution of electromagnetic radiation); yycombating electromagnetic radiation of LF and MF band on the way of their propagation (method of EMF source isolation; method of EMF absorption, i.e., shielding EMF on the way of propagation by absorbing materials and constructions; method of removal from the source to meet

EMF levels of hygienic standards);

yyorganisational measures (time protection method, i.e., reducing the time of the source is exposed to the population, etc.).

PRACTICE

1.  Carry out an eco-hygienic examination of a residential flat (dormitory) according to the scheme. Give hygienic characteristics of the main external and internal sources of low-frequency electromagnetic fields.

2.  Study the subjective reaction of the organism to low-frequency electromagnetic fields and the effect on the central nervous and cardiovascular systems under real living conditions. Propose a set of recommendations to optimise living conditions based on the study results.

The methodology was developed at the Department of Ecological and Prevention Medicine of the Gomel State Medical University.

Task 1. The survey results should be entered into Table 1:

Table 1. Criteria for evaluating EMF effects

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If the index corresponds to the norm, 0 points are assigned. If not, 1 point is assigned. Evaluation of the results: weak impact is 1–4 points, average impact is 5–8 points, strong impact is 9–13 points.

Task 2. Answer the following questions to assess the EMF effects on the human body.

Common symptoms:

1.  Do you notice a concentration disturbance? 2.  Do you experience headaches?

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