Safety of base stations: departure to measure the density of the electromagnetic field

The base station is installed on the building of the central heating station next to residential buildings and a school, therefore it causes serious concern to residents and parents of schoolchildren.

The base station of cellular communication cannot just be turned on and on. To begin with, it is necessary to prepare a project with calculations of the level of the electromagnetic field, conduct its expertise from an independent organization, establish a base station, and obtain the opinion of Rospotrebnadzor. To obtain a conclusion, measurements of the radiation intensity near the antennas and at special control points are carried out. They are performed by experts of an independent organization. Only after receiving all documents base station include broadcast.

Today I will talk about how measurements of the radiation level from this base station were carried out in a residential area of Moscow.
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First, a little theory

The main purpose of the on-site check is to measure the radiation level where people are. In the case if buildings get in the direction of radiation, then control points must be put there. Measurements are taken at the entrance to the building and inside.
With regard to the choice of points in the premises, it is not only the height of the base station antennas that is important, but also the orientation of the windows of the room in which measurements are made, relative to the direction of radiation of the antennas.
Elevated levels of electromagnetic fields are noted only at windows in rooms located in the immediate vicinity of the base station 0-100 m at the same height as the antennas installed. This happens either in the event of a change in the urban planning situation (construction of new buildings in the immediate vicinity of the base station), or if the agreed design solutions are not followed (change in the antenna suspension height, azimuth, angle of inclination).
Most often, design solutions provide for such equipment placement, in which the levels of electromagnetic fields in places with population stay do not exceed the maximum permissible values - 10 µW / cm ² .

Now let's get down to practice.

Specialist FBUZ "Center for Hygiene and Epidemiology in the city of Moscow" with a special device made measurements of radiation indicators at a distance of 15 m from the building where the base station is located, and on the playground.

On a footpath 15 meters from the building of the substation - an indicator of 0.03 μW / cm ² at a rate of 10 μW / cm ²

The substation is located next to the school building, so it was necessary to take measurements in the classrooms on all four floors, the windows of which look onto it. The results prove that nothing threatens the health of schoolchildren.

In the classroom on the 4th floor, at a distance of 0.5 m from the window, the indicator is less than 0.01 μW / cm ² at a rate of 10 μW / cm ² .

Measurements were taken on the territory of a kindergarten 100 meters from the base station. The results of measurements at several points in the territory and inside the building of the kindergarten proved that everything is in order - the indicators on the device are several dozen times lower than the sanitary norms.

5 meters from the entrance to the kindergarten building - indicators 0.02 µW / cm ²

In conclusion, and for the sake of interest, we measured the radiation level during an incoming call to the phone of one of our employees 20 meters from the base station. We are convinced of the low radiation intensity in this case as well.

Check radiation from the phone during a call - indicators 0.11 µW / cm ²

The result of the measurement:

At a radiation rate of 10 μW / cm ² , the maximum recorded radiation does not exceed 0.10 μW / cm ² .
For comparison, the microwave oven emits approximately 20-30 μW / cm ² , depending on the model, and the Wi-Fi home router, 0.1-0.3 μW / cm ² .

How is the base station received?

The last stage of the base station construction is the study of the electromagnetic field level. This is done like this:

Even before the construction of the base station, the operator calculates the effects of radiation: on the basis of information about all buildings, their height, their purpose using special programs, radiation levels are calculated in horizontal and vertical planes. Based on the calculations, a project is being prepared (sanitary passport).
Then the project is examined by accredited organizations. Calculations are checked. If necessary, they may require changing the direction, location, height of antennas, and reducing the radiation power. It turns out the expert opinion on the placement.
Then you need the conclusion of Rospotrebnadzor on placement. Already collected documents are transferred to the Rospotrebnadzor, where specialists of relevant departments study them, conduct their own expertise, and with a positive decision, the operator receives a sanitary-epidemiological conclusion on the placement of a radio transmitting facility.
Upon completion of work, measurements are made on site. For this, the station is temporarily switched on for the duration of the measurement. Measurements are taken next to each antenna and at special test points around. In case of non-compliance with SanPin standards (excess), measures are taken to reduce the power of the radiating antennas.
But that's not all. Now the certified organization must verify the compliance of the project with reality. Issued a second expert opinion.
And, finally, after this, the conclusion of Rospotrebnadzor on the operation of a radio transmitting facility is issued.

What kind of device?

In this case, the Narda SRM-3006 — a selective electromagnetic field meter — is a system consisting of a main module and measurement antennas for determining electromagnetic fields and their sources in the frequency range from 9 kHz to 6 GHz.

In profile, it is used specifically for safety analysis and measurements of environmental parameters of high-frequency electromagnetic fields. The SRM-3006 covers broadcasting, mobile telephony, and industrial frequencies from the low long-wavelength range to the latest wireless applications, and also evaluates the level of field strength in accordance with international or national standards.

How often are measurements taken?

Measurements are taken when the object is commissioned. Then once every 3 years, or as the base station is upgraded.

Where is the technique described?

The measurement technique is carried out taking into account the guidelines: MUK 4.3.1677-03 "Determination of the levels of the electromagnetic field generated by the radiating technical means of television, FM broadcasting and base stations of land mobile radio communications". MUK 4.3.1167-02 "Determination of the energy flux density of the electromagnetic field in the locations of radio equipment operating in the frequency range 300 MHz - 300 GHz."