Flanders.be en.vmm.be
You are here: Home / Air / Detailed results 2014

Detailed results 2014

VMM continuously performs automatic and semi-automatic measurements.

In the case of automatic measurements, the concentration of pollutants in the surrounding air is immediately shown on the analysis apparatus. The results are disseminated in real time

Pollutant# measuring
Ozone O3 20
Nitrogen oxide NOx 43
Particulate matter - fraction < 10 µm PM10 37
Particulate matter - fraction < 2,5 µm PM2,5 37
Black carbon BC 15
Sulphur dioxide SO2 23
Carbon monoxide CO 4
Volatile organic compounds
(Benzene, toluene, ethylbenzene, xylene)
Meteorological parameters 5


In the case of semi-automatic measurements, a sample of the ambient air is taken which is analysed afterwards in a laboratory. In that way, we calculate the concentration of the pollutant over the sampling period. In most cases this is one day, one week or one month. Sampling is done by means of a filter, an adsorption tube, a passive sampler or a precipitation jar. Semi-automatic measuring is done for the following pollutants summarized in the table below.


Pollutant# measuring stations

Heavy metals in PM10 fraction of particulate matter
lead, cadmium, zinc, copper, nickel, arsenic, chronium, antimony, manganese, mercury

Pb, Cd, Zn, Cu, Ni, As, Cr, Sb, Mn, Hg

Heavy metals in dust deposits
lead, cadmium, zinc, copper, nickel, arsenic,
chronium, antimony, manganese, mercury
Pb, Cd, Zn, Cu, Ni, As, Cr, Mn, Hg, iron


Dioxins and PCBs in dust deposits              
Acidifying depostion                                                  
N and S
Polycyclic aromatic hydrocarbons           


Results per parameter

Select an item below for detailed results:

Particulate matter and black carbon

In 2014, all Flemish measuring sites met the European objectives for the PM10 fraction of particulate matter for the first time. The annual limit value of 40 µg/m³ was met in all measuring stations, with annual average PM10 concentrations of 20 to 30 µg/m³.

The daily limit value was met for the first time since the records began in 1996 at all 37 measuring stations. This daily average limit value of 50 µg/m³ may not be exceeded more than 35 days per year. The WHO guidelines for particulate matter are stricter and were not achieved anywhere. A slightly decreasing trend of PM10 in recent years was witnessed, in terms of the annual average and the number of days with a daily average above 50 µg/m³. The figure below shows the annual PM10 concentrations calculated by modelling.Map Flanders PM10

Flanders measures PM2.5 as well, which is the fine fraction of particulate matter. All results were below the future annual European limit value of 25 µg/m³ that enters into force in 2015. Although the trend for PM2.5 is downward, the stricter WHO guideline value was exceeded at all measuring stations.

A specific fraction of particulate matter is soot. Soot particles originate from combustion processes. VMM measures the concentration of black carbon as a means for measuring the soot concentration in the ambient air. The concentrations of black carbon varied from 0.8 µg/m³ at a rural measuring site to 3.1 µg/m³ at a traffic-oriented measuring station in 2014. Since the start of the measurements in 2007, the soot concentrations have shown a downward trend in urban and in recent years also in industrial areas.

Some research was done on the presence of ultrafine particles. It appears that there’s a large variation between the measurement locations. We detected that the amount varies during the day, as well. The intensity of traffic had an influence on the number of particles. A positive correlation was found with black carbon and NO2.


Nitrogen Oxides

All measuring stations in Flanders respected the European hourly limit value and the alert threshold for NO2. The WHO guideline value for hourly averages was exceeded at six measuring stations, and the WHO guideline value for annual averages at three measuring stations.

The NO2 annual averages at measuring stations in Flanders in 2014 were between 12 and 47 µg/m³. In 2014 there were three measuring sites where the annual average exceeded the 40 μg/m³ European limit. These are located in the port of Antwerp and the Antwerp agglomeration, which were granted an extension until 1 January 2015 for attaining the NO2 annual limit of 40 μg/m³. Until that date an annual limit of 60 μg/m³ applies in these zones, so that no exceedances were recorded in 2014. VMM studies have shown, however, that the problem is not limited to the Antwerp agglomeration and the port of Antwerp. Traffic is also responsible for high local NO2 concentrations in other towns. The impact of a motorway on NO2 is measurable up to a distance of 100 m. This demonstrates that the NO2 issue requires considerable attention. The WHO guideline for hourly averages was exceeded at six measuring stations, and the WHO reference for annual averages at three measuring stations.

The figure below shows the annual NO2 concentrations calculated by modelling.


By grouping the measuring stations into industrial, urban, suburban, rural and traffic-orientated sites, we can see fluctuations in the historical, annual NO2 averages for all these groups until 1989. This was followed by a downward trend until 1994. In the period 1995-1997, we noted a rising trend for all groups of measuring stations. From 1998 through 2014, the concentrations are stable to slightly decreasing. Maximum concentrations were measured at traffic-orientated sites.

NO2 trend


Sulphur dioxide

In 2014, all Flemish measuring stations for SO2 met:

• the European hourly limit value for the protection of human health;

• the European daily limit value for the protection of human health;

• the European alert threshold.

The WHO target value for daily values of SO2 was exceeded at three out of four measuring stations.The annual average for SO2 in 2014 at the Flemish measuring stations varied between 1 and 11 µg/m³. The figure below shows the annual SO2 concentrations calculated by modelling.Map SO2 Flanders

There is a downward trend in the period 1981-2014. This decline was recorded for industrial, urban, suburban and rural measuring stations.

The highest SO2 concentrations were measured at the industrial measuring stations. The decline in SO2 concentrations is a reflection of the decline in SO2 emissions.

Trend SO2



2014 was a ozone year with a limited negative impact on public health and vegetation. In 2 of the 19 measuring stations, the information threshold for ozone was exceeded once. The alert threshold was not exceeded.

•    Nobody in Flanders was exposed to 8-hour average concentrations above 120 µg/m³ (NET60ppb-max8h) on more than 25 days. The maximum in Flanders was 15 days (figure above);

•    The negative impact on health (AOT60ppb-max8h) in 2014 amounted on average in Flanders to 566 (µg/m³).hours, which is well under the objective of 5,800 (µg/m³).hours;

•    The negative impact on crops (AOT40ppb-vegetation) was moderate. The ozone concentrations were, on average, 9,649 (µg/m³).hours on Flemish arable land. The target of 18,000 (µg/m³).hours was met everywhere (figure below).

Ozon kaart NET

Ozon kaart AOT


Carbon monoxide

The most important source of CO in Flanders is a ferrous metal company. The annual average of CO was the highest at the measuring station near that company, namely 0.32 mg/m³. VMM also measured the highest 8-hour average at this measuring station, namely 2.87 mg/m³, which is still well below the EU limit value of 10 mg/m³. All CO concentrations are lower than the WHO guideline values.

The diagram below shows the annual CO concentrations calculated by modelling.



Heavy metals

Certain regions in Flanders are still struggling with pollution from heavy metals. The European limit value for the annual average for lead in particulate matter was met everywhere. For arsenic and cadmium in particulate matter, the European targets were exceeded in the vicinity of non-ferrous plants, and for nickel in the vicinity of a ferrous plant. The pollution and the exceedance of the standards was most pronounced north-east and in the immediate vicinity of the source. This was due to the dominant south-west wind in Flanders and fugitive emissions at low height.

A dispersion model was used to estimate the surface area of the zones where the target values are exceeded and the number of inhabitants living in those zones. For cadmium, this model calculated an area of 0.07 km² near a non-ferrous company, with around 60 inhabitants who are exposed to cadmium concentrations above the target value. Near another non-ferrous company, an area of 0.72 km² was calculated with approximately 2,900 people for whom the arsenic concentrations are too high. If those arsenic concentrations were to remain constant over time at that level, then the additional cancer risk would be between one in 21,000 and one in 81,000 people. In this region the cadmium concentrations were too high as well for 110 people. Further cleanup operations are urgently needed.

Mercury appears in the ambient air, primarily as gas. In 2014, the annual averages at the industrial measuring stations near a chlor-alkali company and near a ferrous company were high in comparison with the background values. Nevertheless, the annual averages were well under the WHO guideline value of 1 µg/m³.

The concentrations of heavy metals in PM10 or in depositions were much higher in industrial areas than in towns or background areas. The evolution in the concentrations of heavy metals in PM10 particulate matter and in depositions at most measuring stations were favorable between 2003 and 2014. The concentrations are decreasing in the industrial surroundings as a result of emission reducing measures. The economic crisis, with a drop in production, also played a role in this regard. The concentrations in background areas remained comparable over time.


Polycyclic aromatic hydrocarbons

In 2014 Flanders easily achieved the European target value of 1 ng/m³ for benzo(a)pyrene, part of the group of polycyclic aromatic hydrocarbons. The WHO states, however, that if the currently measured concentrations were to remain constant over time, then the extra cancer risk is between one in 30,000 to one in 140,000 inhabitants.

The measurements revealed the existence of local sources of benzo(a)pyrene. The concentration of this pollutant increased during winter, due to the intensive use of wood stoves.


Volatile organic components

European legislation defines a limit value for benzene within the group of volatile organic components. All measured values in 2014 were below this limit.

The highest annual average for benzene was measured beside a tar refinery and was 1.18 µg/m³. If the concentrations measured should remain constant over time, then the additional cancer risk in Flanders would be between one in 140,000 and one in 440,000 inhabitants.

VMM measured the highest toluene concentrations near a known source of toluene in the industrial area to the south of the measuring location (3.98 µg/m³). The WHO target value was, however, respected.

Dioxins and PCB's

People absorb dioxins and PCBs essentially through their food. For that reason, it is important that agricultural areas and residential zones are free from dioxins and PCBs. There is, however, no Flemish or European legislation for evaluating the deposition of dioxins and PCBs. Europe only advises an upper limit for the intake of dioxins and PCBs by people. It is on that basis that Flanders calculated threshold values for the deposition of dioxins and PCBs. Given the link with the food chain, only the results from measuring stations in agricultural areas and residential zones are assessed against these threshold values. The threshold values enable VMM to make assessments and to determine which regions require extra attention.

In 2014, 15 of the 24 Flemish measuring stations were located in agricultural areas and residential zones. The results for 2014 indicate that the measured values were higher than the threshold values at half of the measuring locations. Many of these measuring points are located near companies that process scrap metal. The PCB values are higher there than the dioxin values. There is no evidence of a generally falling or rising trend near scrap-processing companies.

Acidifying and euthrophying deposition

VMM monitors acidifying and eutrophying deposition on the basis of the concentration and deposition of the main pollutants that cause acidification en eutrophication.

Assessing the Flemish results from 2014 against the regulations, the following conclusions can be drawn:

•    For the indicative testing against European Directive 2008/50/EC, at all measuring locations the calculated SO2- and NOx-concentrations were below the critical levels for vegetation.

•    All ammonia concentrations of the 17 measuring locations in 2014 were lower than the critical level of 8 µg/m³ determined by the WHO. However, the scientific recommendation of 3 µg/m³ defined to protect plants was exceeded at half of the measuring locations.

The diagram below shows the acidifying deposition calculated by modelling.

kaart verzuring vlaanderen

The diagram below shows the euthrophying deposition calculated by modelling.

kaart vermesting vlaanderen

Meteorological parameters

Weather conditions have an impact on the air quality. That is why VMM also has its own meteorological monitoring network. The results are used to assess the impact on air quality.

2014 was the warmest year since the start of the climatological observations. It was a normal year for sunshine and precipitation. The seasons were quite extreme. The winter and the spring of 2014 were the second and third warmest ever. The summer had a normal temperature, but this season was exceptionally wet. The autumn was the second warmest autumn on record. The wind in 2014 came, as in most years, mainly from the south-west. During the autumn, a higher than normal frequency of easterly to south-easterly winds was observed.

VMM contributes to a better air quality in Flanders. We continuously monitor the air quality by measuring the presence of harmful substances in the ambient air.

  » About VMM

banner joaquin

This is an official website of the Flemish government