Air samples in the room. Air Sampling Procedure

To determine the concentration of harmful substances, it is necessary to take samples of atmospheric air for the beginning. This process is extremely important and painstaking. This is due to the fact that even with the most accurate analysis, the results of an incorrectly taken air intake are distorted. Therefore, there are a number of requirements for this process:

• It is necessary to obtain a sample that corresponds to the actual composition of the air;
• Accumulate in the sample the required amount of the desired substance, so that it can be detected in the laboratory.

Taking air samples depends on several factors:

• The aggregate state of the substance sought in the environment (condensation aerosol, gas, steam);
• Possible chemical interactions of the desired substance with the surrounding atmospheric environment;
• The amount of substances in the air;
• Method of research.

During the research in the laboratory, various methods of sampling air are used. The most common are aspirating and the method of selection into the vessel.

Aspiration method

This is the most common method in hygiene practice. The peculiarity of this technique is aspiration. In other words, it is the filtration of the air under investigation with the help of special substances that are capable of absorbing a certain ingredient from all that passes through it. This substance is called an absorbing medium. Disadvantages of the aspirating method of sampling air:

• This is a very laborious process.
• Takes a lot of time (about 30 minutes). During this period, averaging of the concentration of a toxic substance can occur. And the concentration of the substances sought in the air environment changes too quickly. The procedure for sampling air is carried out by professionals.

Selection in blood vessels

This method is very fast. It is used when limited to a small volume of the investigated air and there is no need to accumulate the desired substance in the sample. This selection uses a variety of containers and vessels: cylinders, bottles, syringes and gas pipettes, as well as rubber chambers. This method of sampling air is very sensitive and accurate.

In practice, several types of aspirators are used. The simplest among them is water. This air sampler consists of a pair of identical glass bottles that have been previously calibrated. These vessels contain about 3-6 liters, are closed with stoppers, from which two glass tubes come out. One of them is long and reaches the bottom of the bottle, the other is short, ends immediately under the cork. The long tubes of a pair of bottles are connected by a rubber tube with a clamp. The absorber is added to the short one. When the clamp opens, the water enters an empty vessel located above the one in which the liquid originally was. At this time, a rarefaction takes place over the surface of the water, through which the investigated air is sucked through the absorber. The speed at such a suction is 0.5 to 2 liters per minute, and the volume of air that has passed through the absorber is the same as the amount of water that has passed from the top bottle to the bottom one.

This method is time-consuming and is one of the most difficult. Convenient for use is the Magunov electro-aspirator. This device combines an electric blower with rheometers, which are glass tubes-rotameters, two of which are needed for measuring the air extraction rate, and the other two are designed for high speed. Low speed is from 0,1 to 1 l / min, large - from one to 20 liters per minute. The lower part of the rotameters is connected to the fittings, which are withdrawn to the front part of the device. Rubber tubes with absorbing devices are attached to these fittings. Thanks to this scheme, you can simultaneously select four samples at once. The upper part of the rotameter has handles of valves, which are also exactly connected to the front part. This helps to regulate the sampling rate of air.

The principle of operation of this device is that during rotation in the network with the help of an electric motor the rotor of the blower rotates. At the same time, pressure is lowered in her body. And the air placed outside the device passes through the fittings. Then comes out. Having learned the time taken for it to pass through the aspirator and its speed, it is possible to determine the volume of air passing through the absorber that joins the fitting.

Existing absorbers are designed to take chemical impurities from the air by means of solid and liquid media. And the absorber, and the environment for it is not chosen by chance. Here, the aggregate states of the substances under investigation are taken into account. And also the need to ensure a long-term contact of the substance itself and the absorption medium.

In the event that the investigated gas or vaporous substance is in the air in large quantities, if the method of its determination is very sensitive, then, accordingly, small volumes of the analyzed air are necessary. For this, one-step sampling methods are needed. They use rubber chambers, calibrated bottles and vessels containing from 1 to 5 liters, as well as gas pipettes of 100-500 ml. However, rubber chambers can only be used if the test substance does not exactly react with rubber. They do not store air for more than three hours. It is pumped there with a bicycle pump. For studies, air is transferred to a calibration bottle or other absorber with an appropriate medium.

Selection by exchange method

When the test air is filled with gas pipettes and bottles, this method is called the exchange method.

Air, which lends itself to laboratory research, is blown through a pipette or bottle many times. The pipette is filled with a rubber bulb, pump. This is possible with open clamps or cranes, if any. At the end of sampling, they are closed. In the case of a calibration bottle, it is equipped with stoppers and two glass tubes. To their outer ends are attached rubber tubes with clamps. Before the start of the selection, the clips are removed. And to one of the tubes is attached a pump or a rubber pear. Then the bottle is blown through the air under investigation many times. At the end of sampling, the tubes are blocked with clamps.

Vacuum method

Air samples in the room are made with a thick-walled calibration bottle. It is needed to create a vacuum in it using a special pump Komovskiy. The investigated air is sucked from the bottle to the residual pressure, which ranges from 10 to 15 mm Hg. Then you need to close the clamp on the rubber tube. Disconnect the vessel from the pump. And put a glass stick into the end of the rubber tube. At the sampling site, the tank opens. It will quickly fill with air due to the equal pressure. At the end of the sampling, the clamp is screwed in, and the glass tube is placed in place of the rubber tube hole.

Pouring method

The sampling of air is carried out using a gas pipette or a calibration bottle. They are filled with a special liquid, which should not react with the test substance and, even more so, dissolve it. For these purposes, simple water is often used. In cases when this option is excluded, resort to the use of saturated (hypertonic) solutions of sodium or calcium chloride.

At the place of sampling, the liquid is poured out, and the vessel is filled with the air being examined. Then the rubber tubes are covered with special clips, and at the ends put glass poles or simply close both valves on a gas pipette.

Sanitary tests

These samples are collected for chemical analysis and determine the total dustiness in the human respiration zone and one and a half meters higher.

Studying the pollution of the air due to the emissions of industrial enterprises, determine the average daily and maximum single concentration of harmful substances in the atmosphere. Sanitary air samples are usually taken at the time of greatest pollution from the windy side of the source. Take a minimum of ten samples at all points and through equal intervals of time. Sampling of atmospheric air lasts about twenty minutes. With increasing distance from the source from which pollution originates (no more than five kilometers, further precise analysis is simply impossible), the duration also increases to 40 minutes.

In order to determine radioactive and carcinogenic substances, a large volume of air must be sucked through the filters. Because in populated areas the elements under investigation are contained in a negligible quantity. In the process of sampling air in large industrial plants, the sampling point occupies an important place in studies of the content of toxic substances (such as gases, vapors) or large amounts of dust. Pollutants are distributed unevenly in production premises or buildings. The air environment is constantly and chaotically mobile. For these reasons, atmospheric sample instruments are located at the place where the work process takes place, at a level of one and a half meters from the floor. This is considered the breath of the workers. For one shift, three tests are taken: at the beginning, middle and end of the work day. During their capture, the humidity, as well as the temperature of the air in the room, must be taken into account. Absorptive devices that are needed to take air samples in industrial plants, resemble glass tubes, which are sealed at the top and fastened with a pair of glass tubes. Through the long tube comes the investigated air. And through the short it goes further to the blower through the rheometer. The lower part of the absorber is intended for absorbing liquid through which the test gas must be sucked. The air sampling of the working area is necessary for the normal functioning of the enterprise and the provision of working conditions for the team. In accordance with the current legislation and the requirements of labor protection is a mandatory process.

Gravitational method of selection

This method of taking a sample of air indoors or outdoors is based on the fact that dense particles, which are weighed in it, settle under the influence of gravity. The Durham sampler is the main device used for gravity sampling of the air environment. The essence of his work is as follows. A special slide is inserted into the device holder, which is covered with glycerin gel. Then it is left in the air for a day. Particles that are carried by air flow settle on a slide. Then, under the microscope, the composition and the number of particles are determined under laboratory conditions. The results are represented by the number of particles that settled on a square centimeter per day. The gravitational method of sampling air is inexpensive and fairly simple, but it also has its drawbacks:

• The results of the analysis may be inaccurate due to factors such as direction, wind speed, precipitation and humidity;
• A small number of particles settle down for a day;
• Large particles fall mainly on the slide;
• The samples are collected by professionals, for this they need special instruments, as well as aspirators for sampling air.

Volumetric method

The essence of this method is that particles that are weighed in the air are delayed by obstacles established by its flows. Air samples in heavy industry should be collected at least once a year. Under the conditions of this method, such samplers are used:

• Rotary. Its collecting surface is covered with a special substance, then it rotates for a certain time with the required speed. The result of the sample with the help of this device is expressed by the number of particles that can settle overnight on one square centimeter. This method excludes the effect of wind direction and velocity on the result of the analysis, which gives a more accurate analysis. The Academy of Allergology and Immunology recommends the use of such a device to find harmful substances in the air.
• Aspiration probe can pass the test air through a membrane filter with a predetermined pore diameter. The collecting surface is needed in order for particles of a certain size to settle on it. This principle is key to Bukhard's spore trap, where the collecting surface can move at a speed of about 2 millimeters per hour. This makes it possible to monitor how the concentration of particles in the air under study changes. The device has a weather vane, and therefore the direction of the wind does not affect the final results.

Evaluation of the results of the gravitational selection method allows one to detect large particles (for example, ragweed pollen). For scientific purposes, more powerful and accurate volumetric methods are used.

Pollution Studies

In accordance with the current legislation, air sampling takes place. GOST 17.2.3.01-86 is necessary for correct analysis and error calculation.

In order to study the degree of air pollution in the Russian Federation, developed a special term - "maximum permissible concentration." To date, the maximum permissible standards have been determined. Concentration in the air of harmful substances should not be more than five hundred substances. Air samples allow you to monitor the situation.

Maximum permissible is considered the most concentrated admixture of atmospheric air, which refers to a certain period of time and periodically or throughout the life of a person will not have a harmful effect on it (long-term consequences are taken into account) or on the environment.

In the case of a high concentration of gases, a breakdown of air is carried out, the voltage in this case is about 33 kV / cm. With increasing pressure, the voltage also increases.

There are laboratories, research institutes and individual qualified specialists who, using modern instruments and high-tech devices, detect and eliminate harmful substances in houses, apartments, offices, land plots, etc. The sampling of air is done by the employees of the sanitary epidemiological stations, Laboratory conditions.

How to Secure Your Home

If you begin to notice that someone from your family members (or yourself) suffers from allergic reactions for incomprehensible and invisible reasons, then you need to analyze the air samples in the room. There are several ways for this. Ordinary dust, mold, radon or various pathogenic microorganisms in the air negatively affect the health of people, especially young children. Sampling of atmospheric air is necessary in case of allergic and other reactions in one of the family members. Methods that will help to analyze the air environment in the premises:

• A carbon monoxide detector must be installed. This device plays an important role and without exaggeration saves lives. To install this small device you only need an outlet. If the sensor has issued a warning sound signal, then the level of carbon monoxide has changed in the apartment . As you know, gas has no color and almost no odor, and therefore the sensor's role is really very great, it can save your life.
• Another way to protect your home is by analyzing the air environment in a room at radon. This is especially useful if the house is located near the place of concentration of uranium in the ground, which can lead to the accumulation of radon. In this case, air samples in the apartment must be carried out regularly. There are kits designed for chemical analysis for the content of radon in the atmosphere. You can use them yourself. Install and leave them for three days. After that, the kit is collected and sent to the laboratory for investigation and verdict.
• You can also buy kits for air tests for the presence of mold spores. To determine whether there is a fungus or mold in the apartment, it is necessary to conduct a microbiological analysis of the air environment. Usually this method is used if someone in the family suffers from allergies or sinusitis. Instruments for analysis you can use yourself. However, to obtain the results, you still need to use the services of the laboratory.
• At home, you can check for air dust mites in the air . This phenomenon is present in almost all houses, especially private ones, close to plantings and forests. However, if the concentration of mites, bugs, fleas is too high, it is almost the same as toxic air. For laboratory analysis, a small vial is produced in which an air sample is placed, and then sent to the laboratory for analysis and obtaining the results.

After the results are obtained, it is necessary to solve the corresponding problems. To eliminate them, there are special groups of people who work on a call.