The change in the gas composition of the atmosphere is the result of a combination of natural phenomena in nature and human activities. But which of these processes currently prevails? In order to find out, we first clarify what pollutes the air. Its relatively constant composition in recent years has undergone significant fluctuations. Consider the main problems of controlling emissions and protecting the cleanliness of the air basin on the example of this work in cities.
Does the composition of the atmosphere change?
Environmentalists consider air pollution a change in its average values collected over a long time of observation. They occur as a result of many types of environmental impact of society, as well as due to natural processes. For example, substances that pollute the air and change the gas composition of the atmosphere are formed as a result of respiration, photo- and chemosynthesis in the cells of living organisms.
In addition to natural pollution, there is anthropogenic pollution. Its sources can be emissions from any production facilities, gaseous wastes from the household industry, and vehicle exhausts. This is exactly what pollutes the air, threatens human health and well-being, the state of the whole environment. The main indicators of the composition of the atmosphere should remain unchanged, such as in the diagram below.
The content of some components in the atmosphere is insignificant, but it is taken into account when deciding which substances pollute the air and which are harmless to living organisms. In addition to the main ones, the table located a little lower also includes constant components of the air environment, the content of which increases during the process of volcanism, economic activity of the population (carbon dioxide and nitrogen dioxide, methane).
What does not pollute the air?
The gas composition of the atmosphere over the oceans, seas, forests and meadows, biosphere reserves changes less than in cities. Of course, substances also enter the environment over the above natural objects. Gas exchange in the biosphere is ongoing. But in ecosystems, the process that does not pollute the air predominates. For example, in forests - photosynthesis, above water bodies - evaporation. Bacteria fix nitrogen from the air, plants secrete and absorb carbon dioxide. The atmosphere above the oceans and seas is saturated with water vapor, iodine, bromine, chlorine.
What pollutes the air?
Compounds hazardous to living organisms are very diverse, in total more than 20, 000 pollutants of the biosphere are known. In the atmosphere of megacities, industrial and transport centers, there are simple and complex gaseous substances, aerosols, small solid particles. We list which substances pollute the air:
- carbon monoxide and carbon dioxide (mono- and carbon dioxide);
- sulfuric and sulfur dioxide (sulfur dioxide and trioxide);
- nitrogen compounds (oxides and ammonia);
- methane and other gaseous hydrocarbons;
- dust, soot and suspended particles, for example, ores at mining sites.
What are the sources of emissions?
Harmful substances polluting the atmospheric air enter the atmosphere not only in the gas and vapor state, but also in the form of tiny drops, solid particles of different sizes. The pollution received from enterprises and transport is recorded for specific compounds and their groups (solid, gaseous, liquid).
The concentration of constant and variable air components varies during the day, according to the seasons. When calculating the content of pollutants, atmospheric pressure, temperature, and wind direction are taken into account, since meteorological conditions affect the composition of the surface layer of the atmosphere. Changes in the concentrations of most components, such as carbon dioxide, occur not only during the year. An increase in the amount of CO 2 in the last hundred years has been noted (greenhouse effect). In some cases, changes in the concentrations of substances are caused by natural phenomena. These can be volcanic eruptions, spontaneous exits of poisonous compounds from under the ground or water in certain areas. But more often, human activities lead to adverse changes in the composition of the atmosphere.
What pollutes the air on Earth? Natural and man-made sources of emissions of harmful compounds. The latter are stationary (pipes of enterprises, boiler houses, fuel dispensers of gas stations) and mobile (different types of transport). We list the main objects from which substances polluting the air come:
- operating enterprises of many industries;
- quarries where mining is carried out;
- automobiles (pollute the air when burning fuel derived from oil, gas and other carbon-containing substances);
- gas and liquid fuel stations;
- boiler houses using fossil fuels and products of their processing;
- landfills and landfills where air pollutants are formed as a result of decay, decomposition of industrial and household waste.
Agricultural land, such as fields, gardens, vegetable gardens, also contribute to the negative change in the composition of the atmosphere. This is due to the work of equipment, fertilizing, spraying with pesticides.
What is the main source of air pollution?
Many harmful compounds enter the atmosphere during missile launches, waste incineration, fires in settlements, forests, fields and steppes. In densely populated regions, the most significant contribution to the change in the composition of the surface layer of the atmosphere is made by vehicles. According to various estimates, it accounts for 60 to 95% of all gaseous emissions.
What pollutes the air in the city? The population of urbanized countries is particularly affected by the toxic products of the burning of fuels and fuels. Particulate emissions include particulate matter such as soot and lead, liquid and gaseous compounds: sulfur dioxide, carbon monoxide, nitrogen oxides, hydrocarbons and their derivatives.
Factories pollute the air in industrial regions where industries that process metal ores, salts, oil, coal and natural gas are developed. The composition of the emissions varies depending on the set of industries in a particular region of the country. The polluted air in cities often contains combustion products, among them there are many carcinogens, for example, dioxin. Smoke appears due to forest, steppe and peat fires, burning leaves and garbage. More often, tree plantings and waste burn in the vicinity of cities, but it happens that even directly on the streets they set fire to foliage and grass.
What substances contain emissions from industry and transport?
What pollutes the air in the city? The industrial centers operate industrial, transport, utilities and construction enterprises. Each object individually and all together have a technogenic impact on the environment. Often, pollutants interact with each other. Most often, dissolution of non-metal oxides in water droplets takes place - this is how acid mists and rains form. They cause irreparable damage to nature, human health and architectural masterpieces.
Gross pollutant emissions in cities reach hundreds and thousands of tons. The largest volume of toxic compounds comes from the enterprises of the metallurgical, fuel and energy, chemical, and transport industries. Factories pollute the air with toxic substances: ammonia, benzapyrene, sulfur dioxide, formaldehyde, mercaptan, phenol. The emissions of a large industrial enterprise contain from 20 to 120 types of compounds. To a lesser extent, harmful compounds are formed at combines in the food and light industry, in educational, health and cultural institutions.
Are combustion products of organic debris dangerous?
In cities, it is forbidden to burn fallen leaves, grass, pruning, packaging, building materials and other industrial and household waste. Caustic smoke contains substances that pollute the air. They harm the health of people, generally worsen the quality of the environment.
It is alarming that some citizens and employees of enterprises do not understand that they violate the rules of improvement, aggravate the already unfavorable environmental situation, when garbage heaps and manure are burnt in their plots, and they burn waste in containers in the yards of multi-storey buildings. Very often in the garbage there are plastic bottles, film. This smoke is especially harmful due to the thermal decomposition products of polymers. In the Russian Federation, penalties are provided for the incineration of garbage within the boundaries of a settlement.
When parts of plants, bones, animal skins, polymers and other products of organic synthesis are burned, carbon oxides, water vapor, and a few nitrogen compounds are released. But these are not all substances that pollute the air, which are formed during the burning or decay of waste, household garbage. If the leaves, branches, grass and other materials are wet, then more toxic substances are released than harmless water vapor. For example, when 1 ton of wet foliage smolders, about 30 kg of carbon monoxide (carbon monoxide) is released.
Standing next to a smoldering rubbish heap is like being on the most gas-polluted street in a metropolis. The danger of carbon monoxide is that it binds blood hemoglobin. The resulting carboxyhemoglobin can no longer deliver oxygen to the cells. Other substances that pollute the air can cause malfunctioning of the bronchi and lungs, poisoning, exacerbation of chronic diseases. For example, when inhaling carbon monoxide, the heart works with increased stress, since not enough oxygen is supplied to the tissues. In this case, cardiovascular diseases may worsen. An even greater danger is the combination of carbon monoxide with pollutants in industrial emissions, vehicle exhausts.
Pollutant concentration standards
Harmful emissions come from metallurgical, coal, oil and gas processing plants, energy facilities, construction and utilities. The radioactive contamination from the explosions at the Chernobyl nuclear power plant and nuclear power plants in Japan has spread globally. There is an increase in the content of carbon oxides, sulfur, nitrogen, freons, radioactive and other hazardous emissions at different points on our planet. Sometimes toxins are found far from the place where enterprises polluting the air are located. The situation that has arisen is an alarming and difficult to solve global problem of mankind.
Back in 1973, the relevant committee of the World Health Organization (WHO) proposed criteria for assessing air quality in cities. Experts found that the state of human health for 15-20% depends on environmental conditions. Based on many studies in the 20th century, acceptable levels of major pollutants that were harmless to the population were determined. For example, the average annual concentration in the air of suspended particles should be 40 μg / m 3. The content of sulfur oxides should not exceed 60 μg / m 3 per year. For carbon monoxide, the corresponding average is 10 mg / m 3 for 8 hours.
What is the maximum permissible concentration (MPC)?
The Decree of the Chief State Sanitary Doctor of the Russian Federation approved the hygienic standard for the content of almost 600 harmful compounds in the atmosphere of settlements. This is the MPC of pollutants in the air, compliance with which indicates the absence of adverse effects on people and sanitary conditions. The standard indicates the hazard classes of compounds, their content in the air (mg / m 3). These indicators are refined when new data on the toxicity of individual substances appear. But that is not all. The document contains a list of 38 substances for which a ban on emissions was introduced due to their high biological activity.
How is state control carried out in the field of atmospheric air protection?
Anthropogenic changes in the composition of air lead to negative consequences in the economy, health deteriorates and life expectancy of people decreases. The problems of increasing the influx of harmful compounds into the atmosphere are of concern to both governments, state and municipal authorities, and the public, to ordinary people.
The legislation of many countries provides for environmental engineering surveys before starting construction, reconstruction, modernization of almost all objects of the economy. The pollutants in the air are being rationed and measures are taken to protect the atmosphere. The issues of reducing the anthropogenic pressure on the environment, reducing emissions and discharges of pollutants are being addressed. Russia has adopted federal laws on the protection of the environment, atmospheric air, and other legislative and regulatory acts governing environmental activities. State environmental control is carried out, pollutants are limited, emissions are regulated.
What is MPE?
Air polluting enterprises should take an inventory of the sources of harmful compounds into the air. Usually this work finds its logical continuation in determining the maximum permissible emissions (MPE). The need to obtain this document is associated with the regulation of the technogenic load on the atmospheric air. Based on the information that is included in that MPE, the enterprise receives a permit to release pollutants into the atmosphere. Regulatory emissions data are used to calculate payments for negative environmental impacts.
If there is no MPE volume and permission, then enterprises pay 2, 5, 10 times more for emissions from pollution sources located on the territory of an industrial facility or other industry. Rationing of pollutants in the air reduces the negative impact on the atmosphere. There is an economic incentive to carry out measures to protect nature from the entry of foreign compounds into it.
Payments for environmental pollution from enterprises are accumulated by local and federal authorities in specially created budget environmental funds. Financial resources are spent on environmental activities.
How to clean and protect the air in industrial and other facilities?
Purification of polluted air is carried out by different methods. Filters are installed on the pipes of boiler houses and processing plants, and there are dust and gas capture systems. Through the use of thermal decomposition and oxidation, some toxic substances are converted into harmless compounds. Capture harmful gases in emissions is carried out by condensation methods, sorbents are used to absorb impurities, catalysts for purification.
Prospects for activities in the field of air protection are associated with work to reduce the release of pollutants into the atmosphere. It is necessary to develop laboratory control of harmful emissions in cities, on busy traffic routes. Work should be continued on the introduction of systems for collecting particulate matter from gaseous mixtures in enterprises. We need cheap modern devices for cleaning emissions from toxic aerosols and gases. In the field of state control, an increase in the number of posts is required to check and adjust the toxicity of automobile exhaust gases. Energy industry enterprises and motor vehicles should be converted to less harmful (from the environmental point of view) types of fuel (say, natural gas, biofuel). During their combustion, less solid and liquid pollutants are released.
