Ensuring air quality assessment and monitoring of quality indicators is regulated by Law no. 104/2011 on ambient air quality, which provides for the air quality assessment to be carried out by measurements at fixed locations or, as the case may be, by the mathematical modeling of dispersion of pollutants emitted into the atmosphere. Also, based on the air quality assessment, the number, type and location of fixed measurement points and assessed pollutants shall be determined.

The classification of the A, B or C areas in the zones and agglomerations was based on the results of the national air quality assessment using both measurements at fixed locations, carried out with the help of measuring stations forming part of the Network The National Air Quality Monitoring Authority, which is managed by the central public authority for environmental protection, and based on the results obtained from the mathematical modeling of the dispersion of pollutants emitted into the air.

In areas and agglomerations, in areas under assessment A for sulfur dioxide, nitrogen dioxide and nitrogen oxides, particulate matter, lead, benzene, carbon monoxide, ozone, arsenic, cadmium, mercury, nickel and benzo ( A) ambient air quality assessment shall be carried out by measurements at fixed locations. These fixed measurements may be supplemented by modeling techniques and / or indicative measurements.

In areas and agglomerations in areas classified as B-rated for sulfur dioxide, nitrogen dioxide and nitrogen oxides, particulate matter, lead, benzene, carbon monoxide, ozone, arsenic, cadmium, mercury, nickel and benzo ( A) ambient air quality assessment may be achieved by using a combination of fixed measurements and modeling techniques and / or indicative measurements.

In areas and agglomerations in areas classified as C for sulfur dioxide, nitrogen dioxide and nitrogen oxides, particulate matter, lead, benzene, carbon monoxide, ozone, arsenic, cadmium, mercury, nickel and benzo ( (A) modeling techniques or objective estimation techniques or both are sufficient to assess ambient air quality.

In Order no. 36/2016 lists the administrative-territorial units drawn up following the classification in the zones for evaluation of the areas and agglomerations listed in Annex no. 2 to Law no. 104/2011 on ambient air quality.