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 prevails at the present time? In order to find out, we first clarify what pollutes the air. Its relatively constant composition has been subject to significant fluctuations over recent years. Let's take a look at the main issues of emissions control and air pollution, using this work in cities as an example.
Is the composition of the atmosphere changing?
Air pollution is considered by environmentalists to be a change in its average values collected over a long period of observation. They occur as a result of many types of society's impact on the environment, 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, there is anthropogenic pollution. Its sources can be emissions of anyproduction facilities, gaseous waste from the domestic industry, transport emissions. This is exactly what pollutes the air, threatens human he alth and well-being, the state of the entire 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. The table below, in addition to the main ones, also includes permanent components of the air environment, the content of which increases during volcanism, economic activities of the population (carbon and nitrogen dioxide, methane).
What doesn't pollute the air?
The gas composition of the atmosphere over oceans, seas, forests and meadows, biosphere reserves changes less than in cities. Of course, substances also enter the environment above the above natural objects. Gas exchange in the biosphere is ongoing. But in ecosystems, the process that does not pollute the air prevails. For example, in forests - photosynthesis, above water bodies - evaporation. Bacteria fix nitrogen from the air, plants release and absorb carbon dioxide. The atmosphere over the oceans and seas is saturated with water vapor, iodine, bromine, chlorine.
What pollutes the air?
Compounds dangerous for living organisms are veryare 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. Let's list what substances pollute the air:
- carbon monoxide and carbon dioxide (mono- and carbon dioxide);
- sulfuric and sulfurous anhydrides (di- and sulfur trioxide);
- nitrogen compounds (oxides and ammonia);
- methane and other gaseous hydrocarbons;
- dust, soot and suspended particles, such as ores in mining sites.
What are the sources of emissions?
Harmful air pollutants enter the atmosphere not only in the gas and vapor state, but also in the form of tiny droplets, solid particles of different sizes. Accounting for pollution coming from enterprises and transport is carried out for specific compounds, their groups (solid, gaseous, liquid).
The concentration of constant and variable air components changes during the day, according to the seasons. When calculating the content of pollutants, atmospheric pressure, temperature, 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. There has been an increase in the amount of CO2 in the last hundred years (greenhouse effect). In some cases, changes in the concentrations of substances are due to natural phenomena. It could be volcanic eruptionsspontaneous releases of poisonous compounds from underground or water in certain areas. But more often, human activity leads to adverse changes in the composition of the atmosphere.
What pollutes the air on Earth? Natural and anthropogenic 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). Here are the main sources of air pollutants:
- working enterprises in many industries;
- mining quarries;
- cars (polluting the air when burning fuels derived from oil, gas and other carbonaceous substances);
- filling stations for gaseous and liquid fuels;
- boiler plants using combustible fossils and products of their processing;
- landfills and landfills, where air pollutants are formed as a result of decay, decomposition of industrial and domestic waste.
Agricultural land, such as fields, orchards, orchards, also contribute to the negative change in the composition of the atmosphere. This is due to the work of machinery, fertilization, spraying with pesticides.
What is the main source of air pollution?
A lot of harmful compounds are released into the atmosphere during rocket launches, waste burning, fires in settlements, forests, fields and steppes. In densely populated regions, mosttransport makes a significant contribution to the change in the composition of the surface layer of the atmosphere. 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 toxic products of combustion of fuels and fuels. The composition of harmful emissions contains solid particles, 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 processing metal ores, s alts, oil, coal and natural gas are developed. The composition of emissions varies depending on the set of industries in a particular region of the country. Polluted air in cities often contains combustion products, among them there are many carcinogens, such as dioxin. Smoke appears as a result of forest, steppe and peat fires, burning leaves and debris. More often, tree plantations and wastes burn in the vicinity of cities, but it happens that even directly on the streets they set fire to leaves and grass.
What substances are emitted from industry and transport?
What pollutes the air in the city? Industrial, transport, communal and construction enterprises operate in industrial centers. Each object individually and collectively has a technogenic impact on the environment. Often pollutants interact with each other. Oftenthere is a dissolution of non-metal oxides in water droplets - this is how "acid" fogs and rains are formed. They cause irreparable damage to nature, human he alth and architectural masterpieces.
Gross emissions of pollutants 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 food and light industry plants, in educational, he alth and cultural institutions.
Are organic waste combustion products dangerous?
It is forbidden to burn fallen leaves, grass, branch cuttings, packaging, building materials and other industrial and household waste in cities. Acid smoke contains substances that pollute the air. They harm people's he alth and generally worsen the quality of the environment.
It is alarming that individual citizens and employees of enterprises do not understand that they violate the rules of improvement, aggravate the already unfavorable environmental situation when they burn garbage heaps and manure on their plots, in the yards of multi-storey buildings they set fire to waste in containers. Very often in the garbage there are plastic bottles, film. This smoke is especially harmful due toproducts of thermal decomposition of polymers. In the Russian Federation, there are pen alties for burning garbage within the boundaries of a settlement.
When parts of plants, bones, animal skins, polymers and other products of organic synthesis burn, carbon oxides, water vapor, and some nitrogen compounds are released. But these are not all substances that pollute the air, which are formed during the combustion or smoldering of waste, household garbage. If leaves, twigs, grass and other materials are wet, then more toxic substances are released than harmless water vapor. For example, smoldering 1 ton of wet foliage releases about 30 kg of carbon monoxide (carbon monoxide).
Standing next to a smoldering rubbish heap is like being on the busiest 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 atmospheric air can cause disruption of the bronchi and lungs, poisoning, exacerbation of chronic diseases. For example, when carbon monoxide is inhaled, the heart works with an increased load, since not enough oxygen is supplied to the tissues. In this case, cardiovascular disease 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 andgas processing plants, energy facilities, construction and utility industries. Radioactive contamination from explosions at the Chernobyl nuclear power plant and nuclear power plants in Japan has spread on a global scale. There is an increase in the content of carbon oxides, sulfur, nitrogen, freons, radioactive and other hazardous emissions in different parts of our planet. Sometimes toxins are found far away from the place where the enterprises that pollute 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 He alth Organization (WHO) proposed criteria for assessing the quality of atmospheric air in cities. Experts have found that the state of human he alth is 15–20% dependent on environmental conditions. Based on many studies in the 20th century, permissible levels of the main pollutants that are harmless to the population were determined. For example, the average annual concentration of suspended particles in the air should be 40 µg/m3. The content of sulfur oxides should not exceed 60 µg/m3 per year. For carbon monoxide, the corresponding average is 10 mg/m3 for 8 hours.
What are Maximum Permissible Concentrations (MACs)?
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 whichindicates the absence of adverse effects on people and sanitary conditions. The standard specifies the hazard classes of compounds, their content in the air (mg/m3). These indicators are updated when new data on the toxicity of individual substances become available. But that's not all. The document contains a list of 38 substances for which a ban on release has been introduced due to their high biological activity.
How is state control in the field of atmospheric air protection carried out?
Anthropogenic changes in the composition of the air lead to negative consequences in the economy, deteriorating he alth and reducing life expectancy. The problems of increasing the release of harmful compounds into the atmosphere are of concern to both governments, state and municipal authorities, and the public, ordinary people.
The legislation of many countries provides for engineering and environmental surveys before the start of construction, reconstruction, modernization of almost all economic facilities. Rationing of pollutants in the air is being carried out, measures are being taken to protect the atmosphere. The issues of reducing the anthropogenic load 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 regulating activities in the environmental sphere. State environmental control is carried out, pollutants are limited,emissions are being rationed.
What is MPE?
Enterprises that pollute the air should make an inventory of the sources of harmful compounds entering the air. Usually this work finds its logical continuation when determining the maximum allowable emissions (MAE). The need to obtain this document is related to the regulation of the anthropogenic load on atmospheric air. On the basis of the information included in the MPE, the company receives a permit to release pollutants into the atmosphere. Regulatory emissions data are used to calculate environmental impact charges.
If there is no volume of MPE and a permit, then for emissions from pollution sources located on the territory of an industrial facility or another industry, enterprises pay 2, 5, 10 times more. Rationing of pollutants in the air leads to a reduction in the negative impact on the atmosphere. There is an economic incentive to carry out measures to protect nature from the ingress of foreign compounds into it.
Pollution payments from enterprises are accumulated by local and federal authorities in specially created budgetary environmental funds. Funds are spent on environmental activities.
How is the air cleaned and protected at industrial and other facilities?
Cleaning of polluted air is carried out by different methods. Filters are installed on the pipes of boiler houses and processing enterprises, there are dust and gas trapping installations. Through the use of thermal decompositionand oxidation, some toxic substances are converted into harmless compounds. Capture of 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 highways. Work should be continued on the introduction of systems for capturing solid particles from gaseous mixtures at enterprises. We need cheap modern devices to clean emissions from toxic aerosols and gases. In the field of state control, an increase in the number of posts for checking and adjusting the toxicity of car exhaust gases is required. Energy industry enterprises and motor vehicles should be switched to less harmful, from the point of view of the environment, types of fuel (say, natural gas, biofuels). Their combustion releases less solid and liquid pollutants.
What role do green spaces play in air purification?
It is difficult to overestimate the contribution of plants to the replenishment of oxygen on Earth, the capture of pollution. Forests are called "green gold", "lungs of the planet" for the ability of leaves to photosynthesis. This process consists in the absorption of carbon dioxide and water, the formation of oxygen and starch in the light. Plants emit phytoncides into the air - substances that have a detrimental effect on pathogenic microbes.
Increasing the area of greenplantings in cities is one of the most important environmental measures. Trees, shrubs, herbs and flowers are planted in the courtyards of houses, in parks, squares and along roads. Landscaping the territory of schools and hospitals, industrial enterprises.
Scientists have found out that plants such as poplar, linden, sunflower best absorb dust and harmful gaseous substances from the emissions of enterprises, transport exhausts. Coniferous plantations emit the most phytoncides. The air in pine, fir, juniper forests is very clean and healing.
