Anthropogenic pollution of air and other terrestrial environments is one of the pressing problems of mankind. It grows with the growth of the world population, an increase in consumer demands of people. Because of this, it is becoming increasingly difficult to fight pollution every year. Pollution affects the global climate, the health of humans and other living creatures, the size of fish stocks, the intensity of photosynthesis, and so on. This effect is in most cases negative.
The concept of MPC of harmful substances
In order to somehow normalize the concentration of harmful substances, the concept of the maximum permissible concentration of pollutants was developed and applied. For example, the maximum permissible concentration of carbon dioxide in the atmosphere is 350 ppm (now 410 ppm), and about 600 ppm indoors. Carbon dioxide is the most common, but also the least hazardous of all pollutants. It is mainly dangerous for its impact on the climate, but in this case it is the least harmful of all long-lived greenhouse gases. The problem is that it stands out a lot, and therefore its impact on climate and human health is greater than that of all other pollutants combined.
What is MPC?
MPC is the maximum level of permissible concentration of a particular substance, in the presence of which, even for a long time, there will not be any statistically significant undesirable consequences for nature or man. However, for each organism, the MPC may be different. For example, the maximum permissible concentration of sulfur dioxide for humans is 10 times greater than for plants. Therefore, for each specific case, its own parameter is set. MPC of harmful substances in the air of the working area is always higher than in the air of residential premises.
MPC differences
The MPC values for the same substance can be different in different countries and in different environments. For example, the maximum permissible concentration of lead in water is 0.1 mg / l, the maximum permissible concentration of harmful substances in the air of the working area is 0.001 mg / m 3 , and in atmospheric air it is 0.0003 mg / m 3 . Over time, the MPC values are gradually refined and even revised.
How to determine the maximum permissible concentration?
When calculating the MPC, the results of experiments, numerical calculations, and also statistical data are used. The best option is a combination of all these methods. Nowadays, computer modeling methods, biotests and theoretical predictions for new substances are increasingly being used. Occasional diseases of workers who for a long time inhaled air with the previously set MPC value can become the reason for the tightening of MPC standards. So it was, for example, with the MPC of coal dust in the United States.
MPC Law
The maximum permissible concentration of harmful substances is a hygiene standard, which must be observed without fail. This applies to those organizations that are a source of pollution of the atmosphere and other environments. Data on the permissible concentration of harmful substances are included in sanitary standards, GOSTs and other documents that are mandatory for execution within the given state (in our case, Russia).
MPC are taken into account when designing new industrial facilities, treatment equipment, filters, etc. Monitoring of compliance with the MPC law is carried out by the sanitary-epidemiological service and environmental organizations. As for the quality of water in fisheries, the control over their condition is carried out by the authorities of the Fish Inspection.
Hazard level of the substance
The lower the maximum permissible concentration of a substance, the higher the degree of its danger. For example, for the most dangerous substances (hydrogen sulfide, mercury, arsenic, etc.), the MPC is less than 0.1 mg / m3. For the least hazardous compounds (e.g. ammonia), the maximum permissible concentration is above 10 mg / m 3 . For hydrogen fluoride, the MPC is 0.05 mg / m 3 , for carbon monoxide - 20 mg / m 3 , for nitrogen dioxide - 2 mg / m 3 , and for sulfur dioxide - 10 mg / m 3 .
Among the elements common in nature, zinc, mercury and copper are most undesirable in drinking water.
Limitations of the MPC concept
Even if the maximum permissible concentration of all pollutants is below the MPC level, this is not a guarantee that the air is absolutely safe for health. The reason is that usually there are several pollutants, which means that the sum of their effects will be more than one individual pollutant. Some of the pollutants, when combined, will do more harm than a simple arithmetic sum of the effects of each of the substances separately. Therefore, in Western countries, new approaches are being developed to assess the quality of air and other living environments.
Background concentration of pollutants
This is the amount of harmful substance that is contained in a unit volume of the medium subjected to pollution. For different environments, different definitions of this term apply:
- The background concentration of substances in the atmosphere (or in water) is the concentration of a substance that is created by all sources of pollution. The exception is the subjects.
- Background concentration in water or air is the natural concentration of certain substances that are monitored. Anthropogenic emissions and pollutants from neighboring regions are not included here.
- The background concentration of a substance in the soil is the concentration of pollutants in the soil layer, which is determined in places that do not experience anthropogenic impact, or if this effect is minimal.
Interpretation Methods
The concept of background concentration is interpreted differently. In accordance with the first option, this is the concentration of pollutants that was measured in areas outside the areas where economic activity is carried out. To clarify, determine the range of variation of pollution levels in natural territories. At the same time, the value of background pollution should be determined under conditions as similar as possible to the conditions of the area where the level of anthropogenic pollution will be checked.
According to another interpretation, the background concentration is the concentration that was observed in this place before the appearance of new (investigated) sources of pollution.
That is, two rather different interpretations are obtained. Therefore, the calculation of background concentrations of pollutants can be carried out in different ways. Next, we consider the main causes of air pollution.
The main sources of air pollution
All sources of pollution are divided into natural and man-made. Natural sources include volcanic eruptions, dust rising from the surface of deserts and savannahs, methane released from marshes, forest and peat fires, and so on.
However, the most common problems with air pollution are of anthropogenic nature. The main sources of air pollution include transport, energy, industry, agriculture, household waste dumps, industrial accidents, smoking, construction, mining, domestic and communal activities, wars, holidays, etc. Let us consider each of them individually:
- Transport is considered the most serious source of air pollution. It accounts for 17% of the total harmful emissions into the atmosphere produced by humans. Another disadvantage is that the exhaust pipes of cars are almost at our nose. When a car is operating, different types of pollutants are formed: soot, dust, hydrocarbons, oxides of sulfur, nitrogen, carbon monoxide, heavy metals. One of the harmful components of transport emissions is benzene. Under adverse conditions, benzpyrene can be formed, which is considered a strong carcinogen. All over the world, efforts are being made to reduce transport emissions. More and more people in developed countries now prefer electric cars or bicycles, or use public transport.
- Energy is particularly dangerous for its impact on the climate. It does not affect our health directly. The fact is that emissions in this case are removed from the place where a person lives. During the operation of coal-fired power plants, in addition to 2 , sulfur, nitrogen, carbon monoxide, soot, ash, radioactive elements (in small quantities) are emitted, and so on. During gas stations, emissions are much less. Therefore, they are more preferable to preserve the environment. During accidents, nuclear plants can emit large amounts of radionuclides, but they pose no danger to the climate.
- Industry emits a variety of chemical components, as well as dust, soot, ash. The hazard level of emissions varies greatly from enterprise to enterprise. Many factories are located in cities and have an impact on human health.
- Agriculture is an important source of methane, nitrous oxide, dust and fumes, as well as all the compounds that are associated with the work of harvesting equipment. Cows are recognized as the most dangerous agricultural source of air pollution.
- Landfills for solid household, industrial and construction waste emit organochlorine compounds, dust, soot, asbestos and many other harmful substances. They are an important source of methane emissions. With proper disposal of household waste, the effects of pollution can be minimized.
- During industrial accidents , hydrocarbons, ammonia, chlorine, soot, and sulfur compounds can be released into the atmosphere. In fires, the nature of the emissions directly depends on what is lit. The most harmful in this case is the burning of plastic based on polyvinyl chloride.
- When smoking, various harmful compounds are released into the atmosphere, including heavy metals, radioactive elements, carcinogens, as well as carbon monoxide, soot. Although the volume of these emissions is small, the damage to smoking can be significant for the health of others, since many people prefer to smoke indoors, which leads to the accumulation of pollutants.
- Construction is a source of dust, organic compounds, smelling substances, etc. Their inhalation can cause a headache. The most dangerous type of dust that can form during construction work is asbestos dust.
- When mining, dust is released that may contain harmful, and even radioactive, elements.
- Domestic and communal activities lead to emissions associated with the burning of fuel, the use of atomizers, dusting materials, etc.
- During wars and holidays, dust and smoke are released, which are associated with the burning of gunpowder in firecrackers and ammunition, as well as with the operation of military equipment.