MEPA coordinates two types of monitoring activities: the passive diffusion tube monitoring network and the automated real-time measurement of pollutants.
Passive diffusion tube monitoring network
The diffusion tube network is used to periodically review and assess air quality in Malta and Gozo. By doing this, areas of high pollution are identified and the need for more detailed, continuous automatic monitoring allocated. Thus the diffusion tube network is an important tool in highlighting these hot spots by long-term measurements. Diffusion tubes for various pollutants are installed on a monthly basis in a number of localities in Malta and Gozo. These tubes are then analysed in a laboratory where the concentration for each pollutant is determined. About three tubes (depending on the area) are installed in each locality in near-road, intermediate and urban background sites respectively to be in a better position to determine the way in which the pollutant diffuses throughout the locality.This monitoring started in the year 2000 and is functional to date. In March 2004, the diffusion tube network was restructured in order to have a better spatial coverage over the Maltese Islands. It now includes 43 localities amounting to 134 monitoring sites in Malta and Gozo catering for the following pollutants: nitrogen dioxide, sulphur dioxide, ozone, benzene, toluene, xylene, ethyl benzene and o-xylene. It should be noted that these tubes can give only information about the averaged long-term concentration of these pollutants. Episodes of high concentrations, which may occur in certain sites for a short period of time (e.g. during rush hours) cannot be detected with this method.
Click here for access to diffusion tube maps for the various pollutants. Requests for access to the actual diffusion tube data should be made by email by clicking here.
Real-time measurement network
As opposed to the diffusion tube network, real time air monitoring stations can determine concentrations of most of the pollutants every 15 minutes. The pollutants monitored in real time are ozone, sulphur dioxide, nitrogen oxides, carbon monoxide, volatile organic compounds, gaseous mercury, particulate matter (PM10 and PM2.5) and meteorological variables. The pollutant monitored in each station depends on the nature of the station, its location and purpose. Dust speciation in the PM10 fraction is also taking place at specific locations through periodic measurements around the Maltese Islands.
As part of the requirements of the Preliminary Assessment of Air Quality in Malta (Stacey and Bush, 2002), a need to install four fixed air monitoring stations was identified. Presently, MEPA runs four automated real time measuring stations in Malta which are situated at fixed sites: a traffic site in Msida, at Kordin (at point of maximum ground level concentration for the plume from the Marsa Power Station), an urban background site in Zejtun and in a rural background site in Gharb, Gozo. Three of the above mentioned five stations have been part financed by two European Funding Programmes, namely Transitional Facility 2004 and the European Regional Development Fund 2004-2006. These stations cover all pollutants requiring monitoring and reporting under the Air Quality Framework Directive and the four Daughter Directives.
Click here for access to data from these stations. This data is provisional and may be subject to changes after quality assurance procedures have been completed. Additionally, MEPA also provides the European Environment Agency (EEA) with real time ozone levels as part of EEA’s public information services implemented across Member States.