Urbanizationis a characteristic process of our time, due to the rapid increase in the population and the number of cities, the sharp increase in the role of large cities, the formation of urban agglomerations and the urban way of life.

Urbanization creates a specific environment for human existence, which is characterized by a qualitatively new combination of industrial, social and environmental conditions.

 According to some estimates, more than a million people move to cities in the world during one week. Urbanization processes are especially intense in developing countries. By 2030, almost all of the world's population will live in urban-type settlements. The reason for urbanization is socio-economic factors.

Along with the positive impact on the life of the urban population, which is determined by centralized service communications, negative phenomena are combined with it - pollution of the environment by combustion products during the operation of thermal power plants, vibration, increased noise.

With the growth of cities, their industrial and economic complex becomes more complicated, which leads to pollution of the urban environment with production waste.

The degree of influence of the urban environment on the health of city dwellers is directly related to the size of the city, because as it grows, urban management becomes more complicated - the number of heating and water supply nodes increases, urban transport and other areas of public service expand.

One of the most important characteristics of the urban environment, which determine its specificity, is the microclimate of the city, the condition of which is determined mainly by the degree of its pollution. It affects the overall illumination, the amount of incoming solar and ultraviolet radiation, ionizing radiation, humidity and precipitation, as well as the frequency of fog formation. Some of the elements of the city's microclimate have a direct effect on human health, others have an indirect effect, contributing to the formation of qualitatively new phenomena (smog, persistent air pollution), which then begin to act as independent factors of environmental impact.

One of the types of influence of the urban microclimate on the human body is the temperature regime of the air. A significant increase in average daily temperatures in the central parts of cities occurs due to the accumulation of aerosols in the air, which interfere with nighttime radiation, the active accumulation of heat by stone structures, reduced humidity in many cases, and due to heat emissions from industrial facilities and transport. In general, the thermal energy emitted by a large city is quite large and makes up 3-5% of the volume of energy received from the Sun.

Real "heat islands" often form in cities in the summer. Many researchers believe that their formation may coincide with an increase in the general mortality of the population.

In the atmosphere of the city, the number of condensation nuclei is approximately 10 times, and gaseous pollutants are 5-25 times more than in the countryside. In addition to the direct impact of various pollutants, including aerosols, on people's health, they significantly change the microclimate of cities due to a decrease in insolation, general illumination, and especially the intensity of ultraviolet radiation.

The amount of ultraviolet radiation in cities decreases due to smog by an average of 15-20% (in winter - by 30%, in summer - by 5%), and in cities with metallurgical enterprises, its losses increase to 35%. The duration of sunlight is reduced by 5-15%. Daytime lighting changes to evening lighting for 30 minutes. earlier than in rural areas.

A decrease in the amount of solar radiation has a negative effect on the physiological state of people, increasing fatigue, visual strain, and irritability. Light starvation increases D-vitaminosis and reduces resistance to colds and infectious diseases, worsens metabolism, well-being and mood, and reduces work capacity.

The larger the city, the more the dispersion of ultraviolet rays increases, and a significant part of people does not receive the necessary amount of ultraviolet radiation.

As the amount of ultraviolet radiation decreases, bacterial air pollution increases. The reduced inflow of sunlight slows down the process of photosynthesis by green plants and their release of oxygen. Staphylococcal and streptococcal flora are most often found in the sputum of patients with chronic pneumonia.

Due to the higher temperature in cities, the relative humidity of the air decreases by 2% in winter and by 8% in summer. The presence of a large number of pollutants in the atmosphere contributes to an increase in cloud cover and precipitation by 5-10%, as well as the number of days with fog in winter by 100 and in summer by 30%.

Due to higher temperatures, the atmospheric pressure in the city is lower than in the surrounding area. The wind speed in it is also reduced by 20-30% compared to rural areas. There are 5-20% more windless days in cities than outside them.

Weakening of wind ventilation creates conditions for persistent urban air pollution.

The aquifers under the cities are severely depleted as a result of continuous pumping by boreholes and wells and, in addition, are polluted to a considerable depth.

Residents of large cities have long been drinking water of much worse quality than in villages. Recently, in the CIS, in particular in Ukraine, in most such cities, the quality of drinking water does not meet sanitary standards (there is no way to properly clean huge volumes of water due to a lack of appropriate technologies and funds).

Water pollution is the cause of many diseases. The greatest danger of spreading through water is such infections as cholera, dysentery, typhoid, anthrax, hepatitis, tuberculosis.

The quality of soil in cities, including the suburban green zone, is constantly deteriorating. Soils in urbanized areas are exposed to the same harmful effects as urban air and the hydrosphere, although the soil has a certain possibility of biological self-purification - it breaks down and mineralizes the waste that gets into it. The soils of large cities have high acidity, contain few nutrients, are over-compacted, trampled.

Contamination with household and industrial waste, street garbage leads to the deterioration of the mechanical composition and properties of the soil. A significant impact on soil processes is caused by the pollution and dustiness of cities.

Noise pollution of the urban environment is an important problem. Since the sources of noise are various industrial enterprises, transport, various institutions in the field of service and the very life of the population, its greatest intensity is characteristic of cities, and within them the degree of its detection varies depending on the geography and strength of the noise sources.

The specific conditions of the environment of the modern city include the biological effect of the electromagnetic field (EMF), which is created by various radio and television transmitters, electrified transport lines and power lines. Due to the fact that EMF to one degree or another affects all functions of the human body, maximum permissible levels of electromagnetic energy for various wave ranges have been established and sanitary protection zones against the effects of EMF have been introduced in populated areas.

The source of vibration in cities is motor vehicles, various working mechanisms, and the shallow subway.

The actual problem of the city is the disposal of solid household waste. Accumulation of waste and filth is a source of infection and hatching of insects and rodents, carriers of infections.

The amount of solid household waste depends on many characteristics of the city. It is believed that on average, 250 kg of garbage is accumulated per resident per year (USA – 715 kg, Sweden – 480 kg, Moscow – 270 kg). About 40 million cubic meters are accumulated annually in the housing stock of urban-type cities and towns of Ukraine. m of garbage, which is disposed of at 655 city landfills and 4 incinerators. Regular removal of waste and garbage is the main requirement for the hygiene of the settlement.

All solid waste is transported by specialized transport to specially designated places for disinfection and disposal three times a week, and in large places - daily.

In Ukraine, scheduled and regular removal of garbage is practiced, that is, it is removed at certain times, regardless of accumulation. The removal of the contents of garbage containers to special landfills (landfills) is environmentally and economically unprofitable. For example, in Moscow, the territory of such landfills occupies 108 hectares. Every year in Russia, 10,000 hectares of land suitable for agricultural needs are alienated for landfills for storage and further mineralization of garbage. The most effective method of disposal of household waste is mechanized methods of processing at special plants. For a city with a population of 300,000, a waste processing plant with a capacity of 25,000 to 30,000 tons per year is sufficient. Burning is an effective method of waste disposal.

In Ukraine, only 12% of solid household waste is disposed of at incineration plants (in the cities of Kyiv, Dnipropetrovsk, Kharkiv and Sevastopol). The heavy workload of these enterprises and the lack of preliminary sorting of waste leads to significant violations of the technological regime. Combined with insufficiently efficient flue gas cleaning systems, this creates conditions for air pollution, including highly toxic and carcinogenic substances. Certain problems also exist with the disposal and burial of ash and slag from waste incineration production.

The concentration of industrial enterprises in large and small cities creates another problem - the accumulation of industrial waste. In developed countries, 400-600 kg of industrial waste is generated per inhabitant, and taking into account the waste of the largest industries, this figure is 4-6 tons. Growth rates of waste volume per capita are also high. This indicator for industrial waste is 4-6% per year.

As an ecologically dangerous factor, industrial waste is one of the most significant factors of environmental pollution. The disposal of industrial waste requires the removal of large areas of land, and their transportation and storage becomes a heavy burden for enterprises and the national economy.

The main sources of industrial waste in Ukraine are: steel-smelting production, production of mineral fertilizers, titanium-magnesium production, energy, alumina slurries, galvanic production, coke-chemical production, and iron and manganese ore production. Long-term energy and raw material specialization and the low technological level of Ukraine's industry have put it among the countries with almost the largest absolute amount of generation and accumulation of industrial waste. Every year, more than 1.5 billion tons of solid waste are stored in surface storage facilities. The total volume of their accumulation on the territory of Ukraine, according to minimum estimates, reaches 23-25 billion tons, of which approximately 2% belong to the highly toxic category. The area of land occupied by waste is about 130,000 hectares. There are more than 41,000 tons of them per square kilometer of area, and 480 tons per inhabitant.

There are 2,754 landfills on the territory of Ukraine, with a total volume of about 2,500 million cubic meters for storing industrial waste. 63% of these landfills do not meet sanitary and hygienic requirements for various reasons (unreliable waterproofing, sanitary protection zone is not observed, there are no proper access roads). Many landfills are rebuilt with deviations from the project.

About 180,000 spent mercury lamps are stored in Ukraine in an undamaged manner; galvanic sludges in significant volumes fall into sewage drains; the radioactive waste storage technology that   would guarantee their complete safety has not yet been invented; there are no  specialized plants for the processing of toxic industrial waste; in general, no more than a third of the total amount of waste is disposed of, while the share of secondary raw materials in the total consumption of resources in Ukraine does not even reach 20%.

The analysis of the materials of the sanitary-epidemiological service shows not only the almost complete violation of norms and sanitary rules at the warehouses of enterprises where toxic waste is stored, but also the absence of regulatory and technical documentation on the ground and, as a result, specific recommendations for handling toxic waste. There is also no data on the state of the environment and the risk to the health of the population in the storage areas, and hence there are no measures to prevent the toxic effects of waste.

The high density of people in cities, causing emotional stress, causes, along with other factors, an impact on cardiovascular diseases, diseases of the nervous system and other pathological conditions.

A high concentration of people in the city is a prerequisite for the occurrence of epidemics of influenza and other infectious diseases.

Errors in urban planning can cause a phenomenon called "longing for new cities" - an increase in morbidity among residents of new urban areas, where the living conditions are objectively much better than those in which resettled people lived before. "Longing for new cities" is most often associated with high-rise construction, lack of former close contacts between residents, separation from the usual social and psychological environment. This phenomenon can also be called a kind of nostalgia for the usual conditions of existence.

Are there ways to protect the urban environment from local pollution? Yes, there are many of them.

First of all, this is the transition to waste-free and low-waste technologies. They include a set of measures to reduce losses in the production of raw materials, fuel and energy, maximum efficiency and economy of their use; reuse of waste in a given or other technical process or its safe return to the environment. The creation of such technologies is connected with the development of fundamentally new means of production, a complete reconstruction of traditional technology, etc.

One of the main directions in the development of zero-waste and low-waste technologies is the utilization of emissions, the integrated use of raw materials and materials, the creation of production with a closed cycle, without emissions into the atmosphere and the discharge of wastewater of particularly harmful substances. For   emissions treatment, various treatment facilities are being built - catch filters for gaseous substances and dust. Many of the devices for cleaning emissions from toxic gases are based on the absorption or adsorption principle.   If all chemical enterprises collected production waste, they would receive many thousands of tons of such valuable substances,   such as nitric and sulfuric acids, sulfuric anhydride, fluorine and many others. Some by-products (for example, sulfur) can be collected so much that it would not be necessary to extract them in mines. In the production of non-ferrous metals, for example, an average of 1% of ore is used, the rest goes to waste.

Effective measures to improve the air pool   include the removal of industries with the most harmful emissions outside the city limits, the elimination of small boiler houses and the creation of centralized boiler houses with tall pipes, the wide use of gas, low-sulfur and low-ash types of fuel.

In urban planning, planning is carried out using modeling of atmospheric diffusion, air pollution and air currents in wind tunnels, which will allow to optimally place residential buildings away from sources of pollution.

Many measures are taken to reduce the impact of exhaust gases from cars. In the 1960s in the USA, devices were installed on cars that reduce the emission of harmful substances. In order to filter harmful substances, gas neutralizers are widely used today, in which the engine does not have to run on leaded gasoline. But the increase in the number of cars around the world and the limited use of neutralizers in developing countries complicates the solution to this problem. The network of the state environmental service must monitor and bring the amount of emissions of harmful substances with exhaust gases into compliance with the norms. If we talk about Ukraine, then, first of all, this is often done formally, purely visually. At the request of environmentalists, all cars of foreign brands are equipped with such neutralizers. But our leaded gasoline simply disables them. And then they hang under the bottoms of foreign cars just for the human eye. Secondly, our norms are outdated. If the whole of Europe switched to emission restrictions even after the First World War, and in total - after the Second, if, say, the content of CO in Europe cannot be higher than 1.6%, and in America it is generally 1%, then according to our State Standard of 17.2.03.87 the content CO is allowed as much as 3%. By the way, we have created a domestic gasoline catalyst-converter "Titan". It reduces poison emissions by 1.5-3 times, saves from 10 to 26% of fuel, increases engine power up to 15%, that is, it performs a triple task. The opening received high praise, the decision was made in 2003 to equip all cars in Ukraine with "Titan" catalysts, three plants mastered production. But the fateful decision has been delayed until now.

Driving slowly is another way to reduce emissions. In some countries, when the level of pollution becomes very high, drivers are required to reduce their speed or even not to drive at all. Many cities, including Athens and Rome, have taken measures to restrict traffic under certain conditions.

In some cities, to reduce street traffic, bus fares are reduced. In others, drivers who leave their cars in the parking lot for a nominal fee are allowed to ride the bus for free. There are cities where entire road lanes are reserved exclusively for buses and taxis to give these types of transport more freedom of movement.

In the Netherlands, the bicycle is actively promoted as a convenient mode of transport. In several German cities, cyclists are allowed to ride on a one-way street in the opposite direction.

A promising direction is the development of environmentally friendly types of road transport. Offered electric cars, cars on solar batteries, on hydrogen fuel, etc. Most of them are still imperfect and quite expensive. Research is ongoing and further progress is expected.

Green plantations are an effective measure of natural air purification in places of air pollution. A few convincing facts. One hectare of urban green spaces absorbs 8 kg of carbon dioxide per hour, i.e., as much as 200 people emit at the same time. According to estimates, 1 hectare of 20-year-old pine plantations (with an annual growth of 5 cubic meters of wood) absorbs 9.35 tons of carbon dioxide and emits 7.25 tons of oxygen per year. Oak plantations are even more effective: they absorb 18 tons of carbon dioxide and release 13.98 tons of oxygen per year per hectare (Medina, 1977).

The leaves of many trees and bushes absorb some gases, 70% of dust and aerosols settle on them.

When the air is polluted by gasoline vapors, kerosene, and other flammable substances, it is better to plant Karelian birch, weeping willow, sharp-leaved maple, and winter oak - they reduce air oxidation. And such plants as pyramidal poplar, decorative plum, quince, on the contrary, increase air oxidation. Quince is effective in areas with smoky air. Plantations of white acacia, Canadian poplar, white mulberry, etc. will also be useful there.

To assess the state of the atmosphere, pollution control is carried out. Units of measurement are units of concentration of impurities contained in the air. Basically, the weight concentration is determined in milligrams per cubic meter.

The main criterion of air quality is the maximum permissible concentration (MPC) of impurities in the atmosphere - the maximum concentration of impurities that, with periodic exposure or over a long period of time, does not cause harmful effects on humans and the environment as a whole. WHO has established four levels of air pollution: no impact; irritation; chronic diseases; acute diseases When setting MPC, the lowest level of pollution is accepted.

The maximum allowable emission into the atmosphere (MPE) is a scientific and technical standard, which is established on the condition that the content of pollutants in the surface layer of the air from the source or their aggregate did not exceed the standards of air quality for the population, as well as for the flora and fauna.

The forecast of atmospheric pollution is carried out in order to determine the expected level of air pollution. For this purpose, the results of theoretical and experimental studies of patterns of distribution of impurities from various sources depending on meteorological factors are used.

To obtain information about the state of the air basin, a network of control points and stations has been created. An inventory of emissions is regularly conducted - accounting for the main sources of atmospheric pollution, the amount and composition of emissions.

Automatic gas analyzers are used to determine and register the concentration of individual impurities contained in atmospheric air. They make it possible to obtain continuous time characteristics of air pollution and to detect maximum concentrations that are not fixed during periodic air sampling.

Chlorination is a reliable method of cleaning drinking water from the pathogens of the above-listed infections. In most European cities, ozone is used to disinfect water. Both methods have their advantages and disadvantages. When organizing the water supply of cities, it is necessary to provide for the creation of reliable protection zones of water intakes and reservoirs, the reduction of their pollution by industrial emissions due to the use of filters for wastewater treatment, the use of circulating water supply.

It is also possible to successfully solve environmental problems associated with the disposal of household waste. In some countries, solid household waste is considered as a complex   raw material and therefore it is not burned. It is estimated that their composition includes 20-40% waste paper, 2-3% ferrous and non-ferrous metals, 25-40% food waste, 1-5% plastics, 4-6% glass, 4-6% textiles. For example, the Italian firm "Sarain Cecchini" returns 50 tons of ferrous metals and 25 tons of paper fibers to society from 1,800 tons of garbage every day (which is equivalent to saving 400,000 trees). There, granulated organic fertilizer is made from food waste, and polymer film is made from plastics.

In Japan, railway and subway tickets are recycled into toilet paper and cardboard boxes. For example, 9 thousand 130 meter rolls of toilet paper are obtained from 5 tons of tickets.

Thanks to a special method of thermal dissolution of old car tires, 600 kg of oil and 300 kg of associated gas will be obtained from 1 ton of rubber. Carbon black is a filler for plastics, gas is fuel, and oil can be used to produce approximately 200 liters of gasoline, 200 liters of diesel fuel, and 200 liters of fuel oil. At the same time, the profitability is more than 50%. .     The American company "Nike" takes old, worn sneakers and makes them into rubber coverings for running tracks and tennis courts.

In Japan, a method of processing plastics into gasoline, gas or diesel fuel has been developed. One of the rational methods of decontamination and disposal of household waste is its biothermal processing into compost, which is then used as biofuel in protected soil and as organic fuel in the fields. Thermally dried urban sewage sludge can also be used as a fertilizer.

In some countries, municipal landfills are equipped with special installations for obtaining and using biogas, which is formed in waste as a result of microbiological processes.

The problem of industrial waste should be considered as a set of environmental and resource components. The basis for making a decision should be a technical and economic analysis of the problem.

The ecological direction should primarily involve detailed monitoring and classification of waste, determining the degree of their toxicity and impact on the environment. In accordance with this, develop waste storage and storage technologies, evaluate the possibilities of their disposal and neutralization. For environmental hazard analysis, it is advisable to use a generalizing indicator, for example, the environmental hazard coefficient, which   takes into account the hazard class and location conditions - the presence of specially equipped areas, storage containers, etc.

The resource direction involves the evaluation of waste as a source of raw materials: that is, it is about determining the content of valuable components in specific waste, comparing possible technologies for their extraction and estimates of processing and delivery. For this, it is necessary to have systematized information about the presence and expected generation of waste and to know whether there is a demand for such raw materials and in which specific enterprises in the region. That is, it is necessary to create a qualified database of consumers of this waste.

The technical direction of the analysis involves the creation of databases on effective low-waste and ecologically clean technologies by industry, waste disposal and disposal technologies, implementation of an information system for their accounting and use.

Wide use of underground space for the placement of urban construction objects can contribute to the solution of many environmental problems. With the development of the underground space, the efficiency of land use increases, sanitary and hygienic conditions improve.

The aggravation of the problems of rational planning of the structure of cities and the development of landscape architecture led to the emergence of a new direction in ecology - bio-urbanism or arcology. This is ecological architecture, which deals with issues of urban development with maximum consideration of ecological factors, preservation and expansion of green areas, optimization of working conditions and living conditions of the urban population.

The main tasks of  arcology include: maximally taking into account the ecological and sociological-ecological needs of a specific person from birth to old age; bring people closer to nature (creation of green recreation areas near residential areas; ridding them of the monotony of urban space (construction of houses of different configurations, colors, etc.); correct distribution of the population by area (no more than 100 people per 1 ha, construction of microdistricts for 30,000 man with a ratio of low- and high-rise buildings in the ratio of 7:3); preservation of at least 50% of the inhabited city space for green spaces; isolation of the population from traffic routes; creation of conditions for communication between people, etc.

Thus, the urboecosystem is a very complex system in which biological processes, industrial-technical and social conditions must develop without contradictions to each other, and in general provide optimal conditions for human life. It is clear that these conditions are not created by themselves. It takes effort, a smart and far-sighted attitude to the environmental problems of the urban environment.