Экологическая медицина = Ecological medicine. Учебное пособие

of food and about 2,000 grams of water per day. The daily ration of the population of our planet (5 billion people) is more than 4 million tons of food.

Food should fully satisfy humans’ physiological need for nutrients and energy. Physiological need is a necessary combination of nutritional factors to maintain a dynamic balance between humans as a species formed in the process of evolution and the environment, aimed at ensuring the vital activity and reproduction of the species, as well as to maintain the adaptive potential of the organism. Food and food items are designed to satisfy this need.

Food or food items are all objects of the environment and products of their processing, which are used by humans for nutrition as sources of energy and nutrients. It includes raw foodstuffs and plant and animal foods. Food substances or nutrients are chemical compounds that the body uses to build, renew and repair its organs and tissues, as well as to provide energy to compensate for all kinds of energy expenditures.

One type of food contamination is food contamination as a result of anthropogenic environmental pollution. In addition, products can be contaminated with a variety of alien chemical compounds (xenobiotics) that have an adverse effect on the human body. Some toxic substances originally present in plant and animal raw materials, or appearing in them during processing, have a similar effect on the body.

These are so-called antialimentary substances, which include bioinhibitors of proteinases, antivitamins, and demineralising factors. Foreign compounds entering the body as a result of its response are subjected to metabolism and detoxification. The main thing in these processes is the formation of an active intermediate metabolite of the initial foreign compound and its interaction with target cell biomolecules.

The entire variety of xenobiotic metabolism can be divided into two phases:

yythe first phase includes all processes of xenobiotic transformation accompanied by oxidation, reduction, hydrolysis, or detachment of chemical groups of their molecules;

yythe second phase involves the conjugation of xenobiotic molecules with endogenous substrates.

Enzyme systems play the most significant role in metabolic processes. The general orientation of metabolic processes is to transform them into water-soluble compounds, which facilitates their elimination from the body.

91

Chapter 7

MEDICAL ASPECTSTO GUIDETHE INDOOR ENVIRONMENTAL EFFECTONTHE POPULATION

HEALTH STATUS

Motivational characteristic of the topic. It is known that people in the developed world spend up to 90% of their time indoors. This fact indicates that indoor air pollution can have a more significant impact on the body than atmospheric air. In fact, only 40% of pollutants are external. Many factors affect the health of people indoors: temperature, relative humidity, air velocity, etc. Typically, living environment factors are low-intensity. They can be conditions for the disease development, and this is their danger. The hygienic significance lies in the fact that they are not the cause of the disease, but can cause pre-pathological non-specific changes in the organism.

Under the conditions of increased electrification of human settlements, the issue of electromagnetic pollution of living conditions is becoming more and more acute. Scientists all over the world are sounding the alarm, trying to prevent the adverse effects of long-term exposure to electromagnetic radiation on the human body. Consequently, the ecological and hygienic assessment of the air environment in closed rooms is very critical. These issues are part of medical professionals’ duties.

The objective: to consider the environmental and health consequences of indoor pollution and measures to protect against adverse indoor environmental factors.

Tasks:

1.  To show the relationship between the air environment condition in the premises and the morbidity of the population.

2.  To learn how to assess air pollution influence in residential and public buildings.

3.  To learn how to develop preventive measures aimed at improving the air environment of closed premises to reduce the adverse effects on human health.

Requirements for students’ initial knowledge level. To fully master the topic of the chapter, a student should revise the relevant material from the following disciplines:

93

1.  Microbiology, Virology, Immunology: “Ecological environment of microorganisms”, “Microflora of air”.

2.  Medical Biology and Genetics: “Harmful influence of electromagnetic fields on organisms”, “Organism as an environment. Interaction of parasite and host at individual and population levels”.

3.  General Hygiene: “Hygiene of the air environment. Influence of microclimate of premises on human health”.

Review questions from the related disciplines:

1.  The main air pollutants in inhabited spaces and their characteristics. 2.  Characteristics of different ventilation types.

3.  Methods of determining ventilation effectiveness.

4.  The basic parameters of the microclimate of the premises and their regulation.

Questions related to the topic of the chapter:

1.  The importance of housing and hygienic characteristics.

2.  Hygienic requirements for dwelling design, equipment, and maintenance.

3.  Characteristics of factors in the air environment of enclosed spaces that affect human health:

a)tobacco smoke;

b)formaldehyde and other toxic substances;

c)biological factors;

d)natural gas and combustion products;

e)electromagnetic fields.

4.  Air pollution sources in residential and public buildings.

5.  “Sick building syndrome”: causes of development, clinical symptoms, prevention.

6.  Influence of electromagnetic radiation on the human body under real living conditions.

7.  Main directions for prevention of adverse effects of EMR on the human body.

LEARNING MATERIAL FOR THE CHAPTER

Urban residents spend about 70% of their lives indoors, and therefore the indoor environment of residential and public buildings should be the focus of medical attention.

Chemical composition of indoor air. Ensuring complete comfort in modern enclosed spaces can be achieved if microclimatic and air comfort is

94

created. Due to the development and introduction of various chemicals into various sectors of the national economy and, in particular, into civil engineering and everyday life, the air environment of modern residential and public buildings has a multicomponent chemical composition. A special air environment is formed in buildings, which depends on the state of atmospheric air and the power of internal sources of pollution, which primarily include the products of destruction of finishing, polymer materials, human activity, incomplete combustion of gas, etc.

Indoor air quality in terms of its chemical composition largely depends on the quality of ambient atmospheric air. Based on the study of concentrations of one of the most widespread atmospheric pollutants – sulphur dioxide (SO2), specialists note a certain parallelism in outdoor and indoor concentrations of this substance.

CO2 concentrations indoors are about 35% of its atmospheric content. This difference can be explained by the sorption of the substance on building envelopes, interior furnishings (wool carpets, wallpaper, some types of paints, etc.).

In a comparative study of indoor and outdoor concentrations of carbon monoxide (CO), which can occur not only due to air pollution by motor vehicles, but also due to formation inside buildings, such a clear pattern was not observed. In some cases, higher concentrations inside the premises were noted, but in others, the CO content inside the premises when the windows were closed was 77% of the outside. The concentration of nitrogen dioxide inside the premises was about 60% of its content in the atmospheric air.

Studies of the mutual influence of the internal environment of residential and public buildings and the environment are of interest. By mass spectrometric analysis it was established that residential and public buildings are a source of environmental pollution by such substances as ammonia, demethylamine, nitrogen oxides, carbon monoxide and carbon dioxide, hydrogen sulphide, propylamine, mercaptan, phenol, toluene, methanol, vinyl acetate, cresol and others. All these substances are either products of human activity or degradation products of polymeric materials.

Gasified buildings compared to electrified buildings were more powerful sources of release of toxic substances (nitrogen oxides, carbon monoxide, sulphur compounds, ammonia, amino compounds).

Administrative buildings emit 2.5 times fewer harmful substances than residential buildings due to the lack of garbage chutes, laundry, cooking and other processes.

95

Studies have established that concentrations of certain chemical substances in the air of residential premises exceed the level of concern (LOC) for atmospheric air, even without an internal source of pollution. Air pollution by phenol, formaldehyde, acetone, nitrogen dioxide inside the dwellings is higher than in the outside air. This is especially evident at the 1st floor level. The vertical distribution of atmospheric pollutants is not the same. Concentrations of formaldehyde, nitrogen dioxide and acetone increase with increasing height; the highest concentrations are observed on the 3rd floor.

In enclosed and uninhabited residential areas, higher concentrations of sulphur dioxide have been found than in the outdoor air. This can be explained by the ability of sulphur dioxide to sorb and accumulate on the surface of construction finishing materials (plaster, paint, wallpaper, flooring). The greatest amount of sulphur dioxide is absorbed by polymeric coverings (synthetic carpets, linoleum, paint). Thus, buildings do not protect residents from contamination of the atmospheric air. In a number of cases, the chemical load a person experiences indoors exceeds the load he or she experiences outdoors.

One of the internal sources of chemical pollution of indoor air is the products of human life, formed in the process of metabolism – anthropotoxins. Carbon monoxide and carbon dioxide, aliphatic hydrocarbons, ammonia, amines, ketones, phenols, acetone, hydrogen sulphide, alcohols and fatty acids are of particular importance for indoor air composition.

The air environment of unventilated premises was found to deteriorate in proportion to the number of people and the time of their stay in the room. Dimethylamines and hydrogen sulphide exceed LOC for atmospheric air in unventilated premises. Such substances as carbon dioxide, carbon monoxide, and ammonia also exceed or are at LOC levels.

Carbon monoxide concentrations are especially high during gas combustion. During an hour’s operation of a two-burner stove, there is a concentration of carbon monoxide 10–12 mg/m3, nitrogen oxides – 0.11 mg/m3.

During gas combustion, the kitchen air is considerably polluted with carbon monoxide, temperature and relative air humidity increase, the subjects have a decrease of oxyhaemoglobin in blood and exhaustion of organism oxygen reserves (according to the data of functional test with physical load); there is some worsening of central system functional condition.

Concentrations of carbon monoxide, nitrogen oxides and formaldehyde during gas combustion in modern type gasified flats with the same condi-

96

tions of air exchange (100 m3/h) exceed the maximum permissible concentration of atmospheric air not only in the kitchen, but also in living rooms.

One of the most powerful sources of indoor air pollution are construction and finishing materials made of polymers.

Polymeric materials have vast applications. At present, only 100 polymeric materials are listed in municipal buildings. Construction polymeric materials are used for covering floors, walls, thermal insulation of external roofing, waterproofing, sealing and cladding of hinged panels, manufacturing of window blocks and doors, volume elements of prefabricated houses.

The wide use of polymeric materials and the expediency of their use in the construction of residential and public buildings is determined by a number of positive properties that facilitate their use, improve construction quality, reduce its cost. However, numerous studies show that practically all polymeric materials are a source of migration of toxic chemicals into the air, which have a harmful effect on the health of the population. For example, polyvinyl chloride materials (polyvinyl chloride is one of the most common types of polymers used in the finishing of modern residential and public buildings) are sources of benzene, toluene, ethylbenzene, cyclohexane, xylene, butyl alcohol and other hydrocarbons released into the air.

Particle boards based on phenol-formaldehyde and urea-formaldehyde pollute the air environment of residential and public buildings with phenol, formaldehyde, and ammonia. Carpet products made of chemical fibres emit styrene, isophenol, and sulphur dioxide in significant concentrations.

There are significant amounts of acetone, methacrylic acid, toluene, butanol, formaldehyde, phenol, and styrene released into the air from fibreglass used in construction, sound and thermal insulation. Paint coatings and adhesive-containing substances are also sources of indoor air pollution with the following substances: toluene, butyl methacrylate, butyl acetate, ethyl acetate, xylene, styrene, acetone, butanol, ethylene glycol, etc. (a list of some toxic materials is given in Appendix).

The intensity of volatile substances release depends on the operating conditions of polymeric materials – temperature, humidity, air exchange rate, operating time, saturation of the material. The number of harmful substances in the air environment of the room increases depending on the “saturation” of its polymeric material.

A significant disadvantage of polymeric materials is their ability to accumulate large charges of static electricity due to their dielectric properties. Prolonged exposure to static electricity is harmful to health. The presence

97

of charges on the surface of the floor and enclosing structures worsens some air traces and makes it difficult to clean the premises. The recommended permissible level of static electricity field strength is 150 V/cm.

There are a lot of data on atmospheric pollution influence on human health. Currently, there are many cases of toxic fog, each accompanied by increased morbidity and mortality. In areas with polluted atmospheric air there is a higher incidence of respiratory organs, conjunctivitis, skin, allergic and other diseases.

Urban areas have significantly higher morbidity rates than rural areas. Urbanisation determines the nature and frequency of many nervous system diseases. The peculiarities of individual diseases’ distribution are also connected with living conditions in cities. Acute respiratory diseases and flu grow depending on the frequency of intra-urban contacts. Tuberculosis infection is particularly dangerous.

Experience has shown that the most significant role in the future transformation belongs to the system of national measures aimed at improving the productive forces, restraining the growth of large cities, and protecting the environment from air, water, and soil pollution. Planning, technical, sanitary-technical and organisational measures are directed at improving living conditions. The laboratory control of the atmospheric air state is of paramount importance, and devices and means of automation for controlling environmental pollution are being implemented. Practical implementation of the system of automatic monitoring and data collection on atmospheric pollution allows a more complete study of the impact of environmental factors on human health.

The quality of the human environment is regulated by Construction Norms and Regulations, Sanitary Rules and Regulations and a number of sanitary-hygienic standards for certain environmental factors.

Hygienic requirements for housing include the creation of:

1)  favourable spatial parameters of the flat (area per person, height of rooms, utility rooms, open spaces);

2)  an optimal microclimate;

3)  sufficient natural and artificial light;

4)  favourable condition of the air environment in the premises (the size of the air cube per 1 person, the maintenance in the air of anthropotoxins and toxic substances, microorganisms, dust);

5)  favourable conditions for the work, rest, and sleep of people; 6)  optimal conditions for domestic purposes, children’s education; 7)  conditions for the aesthetic design of the dwelling interior.

98

When assessing the quality of the living environment, it is necessary to consider the summation of risk factors in each object of the urbanised environment. According to the authors’ research experience, the following conceptual scheme can be used to provide healthy living conditions in these types of settlements (see Table 7.1).

Table 7.1. Conceptual framework for providing an environmentally sound and hygienically friendly living environment

99

The basic element of a dwelling is a flat, which includes: 1)  living areas (bedrooms, common room, study);

2)  utility rooms (kitchen, bathroom, toilet, shower room, corridor); 3)  outdoor (loggias, balconies, verandas).

Bedrooms should be oriented to the south, not designed as walkthrough rooms. It is possible to have a walk-through common room that is oriented to any direction.

The kitchen should be oriented to the north. The minimum kitchen size is about 7 m2. If the kitchen is used as a dining room, its size should increase to 12 m2.

The size of the front should not be less than 4.5 m2, the bathroom – from 2.5 m2 to 12 m2. The minimum area of the toilet room should be 1.5 m2. The area of storerooms can range from 1.5 to 6 m2.

Hygienic assessment of an flat includes not only a set of rooms, but also their layout: conditions of aeration, ventilation, heating, insolation, natural illumination. From a hygienic point of view, the two-storey layout is the most favourable. A ventilation system is used in this case. In contrast to houses with flats for families, dormitories are intended for single living workers, students of higher and secondary special educational institutions. Blocks of flats and premises in their technical condition, composition, area, location, and equipment must create favourable conditions for residents’ health.

100