MK – NI 004

The indicator shows the portion of urban population potentially exposed at ambient air concentrations of pollutants in excess of the limit value set for human health protection.

Urban population taken into account is actually the total number of inhabitants living in cities with at least one monitoring station. These cities include the capital and other major cities of the Republic of Macedonia. The number of inhabitants is based on the last census carried out by the State Statistical Office in 2002.

Exceedance of air quality limit values occurs when the concentration of air pollutants exceeds the limit values for SO₂, PM₁₀, NO₂ and the target values for O₃ as specified in the Decree on the limit values of levels and types of polluting substances in ambient air and on the alert thresholds, deadlines for the limit values achievement, margins of limit value tolerance, target values and long-term ozone targets (Official Gazette of the Republic of Macedonia No. 50/05, 4/2013), wherein the requirements of the Directive on Ambient Air Quality and Cleaner Air in Europe 2008/50 EC and Heavy Metals Directive 2004/107/EC have been transposed. Where there are multiple limit values (see section on Policy Targets), the indicator uses the most stringent case:

• Sulphur dioxide (SO₂): the daily mean limit value
• Nitrogen dioxide (NO₂): the annual limit value
• Particulate matter of a size up to 10 micrometer (PM₁₀): the daily mean limit value
• Ozone (O₃ ): the short term objective

The percentage of urban population potentially exposed at ambient air concentrations of sulphur dioxide (SO₂), particulate matter sized up to 10 micrometer (PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) above limit values set for human health protection. Ambient air concentrations of sulphur dioxide (SO₂), particulate matter sized up to 10 micrometer (PM₁₀), nitrogen dioxide (NO₂) and ozone (O₃) are expressed in microgram/m³(µg/m³).

What progress has been achieved in reducing the concentrations of pollutants in urban areas in order to achieve the limit values, NO₂ set in the Decree?

In the period from 2004 to 2017, the portion of the population exposed at concentrations of nitrogen dioxide above the limit values set for human health protection ranged between 0 and 69%. The highest percentage of population exposure of 69% was recorded in 2011.

Diagram 1: Percentage of urban population exposed at air pollution in areas where concentrations of pollutants are in excess of limit/target values

Diagram 2: Percentage of population exposed at NO2 annual concentrations in urban areas

Diagram 3: Average annual concentration of NO2

Data coverage: excel

Source: Ministry of Environment and Physical Planning (https://arhiva.moepp.gov.mk/?lang=en)

Investigations have testified the presence of several nitrogen oxides in the air, but the most significant among them are nitrogen dioxide and nitrogen monoxide. These pollutants most often originate from natural sources. However, in urban environments, the main source is the traffic, and industry is minor source. The most toxic of all nitrogen oxides is the nitrogen dioxide, the concentrations of which are dependent on season and meteorological conditions. Namely, concentration of NO is higher in morning hours when the traffic is more frequent, while the intensification of solar radiation during the day leads to transformation of NO into NO₂ resulting in increased concentration of NO₂. Nitrogen oxides influence the content of ozone and other photochemical oxidants in the air. During the spring-summer period, the concentration of NO₂ is higher, while in autumn-winter period, the concentration of NO is higher. The quantity of NO_x increases in winter period due to the higher frequency of traffic.

In the period 2004 to 2017, the portion of population exposed at nitrogen dioxide concentrations above the limit value for human health protection (40 µg/m³mean annual limit value) ranged from 0 to 69%. The highest percentage of 69% population exposure was recorded in 2011.

In 2004, 2006 and 2011, significant portion of the population (55-67%) of the population was exposed at concentrations above 40 µg/m³.

• Methodology for the indicator calculation

The mean annual concentration in a city is calculatedas an average of the mean annual value measured in all monitoring stations located in urban areas. Selected urban stations include stations of the following types: stations measuring traffic pollution, stations measuring industrial pollution and urban background stations.

Uncertainty

• Methodological uncertainty and data uncertainty

In general, data is not representative for all urban environments in the Republic of Macedonia. Compared to the methodology of the European Environmental Agency, where the calculation of the indicator is based only on data produced by the urban background stations, in our calculations we used data from all measuring stations located in urban environments. Also, due to the minimum number of monitoring stations, the calculation of the indicator also took into account the stations where data coverage is below 75% per calendar year. We can also point out as uncertainty in the indicator calculation the fact that the number of inhabitants in cities is based on the census of the population conducted by the State Statistical Office in 2002, instead of estimated number of population for each year.