The purpose of the EMISSION project is the continuous recording of the main regulatory ambient air pollutants and their online visualization on an open internet platform. The experimental phase includes the design/development, calibration and operation/evaluation of advanced medium- and low-cost air pollution monitoring systems, that are based on sensor technology. The EMISSION network is supplemented by the state-of-the-art monitoring station of the National Observatory of Athens (NOA) at Thissio. The EMISSION online platform also provides open data from regulatory stations of the National Air Pollution Monitoring Network (NAPMN) of the Greek Ministry of Environment and Energy, which are in operation in the greater area of Athens.
The data from the regulatory sites (NOA-Thissio and NAPMN) can be used for the evaluation of concentrations against air quality standards defined in the European and National legislation for the protection of human health and the environment. Data from sensor-based systems, since they do not use the standard measurement methods defined in the EU directives, should not be directly compared to established limit values for assessment of compliance or exceedances. Nevertheless, they provide reliable information on the severity of recorded levels and their short-term variability. They are systematically calibrated against reference instruments that use the standard methods at the NOA-Thissio station and therefore provide realistic concentration levels.
EMISSION focuses on the monitoring of gaseous and particle pollutants related to the most serious effects on human health and for which there is a history of high levels and exceedances of concentration limits in the area of Athens. Specifically, the following gaseous pollutants are monitored:
- O3: Ozone
- NO2: Nitrogen Dioxide
- CO: Carbon Monoxide
and also the following particle pollutants:
- PM2.5: Fine Particulate Matter (particle diameter <2.5μm)
- BC: Black carbon
All pollutant concentrations are reported in microgram per air cubic meter (μg m-3) units, and their values are updated on an hourly basis (hourly average values).
According to the project design of EMISSION, the location of monitoring sites is decided with the objective to spatially cover the Athens basin, at the Regional Unit level when using medium-cost systems and at the Municipality level when using low-cost systems. The majority of monitoring sites are of urban background type, being located at an adequate distance from high-traffic roads and therefore are representative of levels in a radius of a few km2, so that they can describe the atmospheric exposure of a large part of each area’s population. Some instruments are also placed at sites of traffic type, to characterize the levels and variability of primary pollutants emitted directly by vehicles.
So far, EMISSION has installed:
- 4 medium-cost systems recording O3, NO2, CO and PM2.5 concentrations. Of these, 3 were placed in urban background locations and 1 in a traffic location. The traffic site is situated in the Regional Unit of the Central Sector of Athens (Mesogeion Avenue) and the background sites cover the Regional Units of the Western Sector of Athens (Peristeri), of the Northern Sector of Athens (Melissia) and of Piraeus (Piraeus Center)
- low-cost systems recording O3, NO2 and PM2.5 concentrations. The first systems have been deployed in urban background locations, in the areas of Gyzi, Aegaleo, Rentis and Pallini
- 2 medium-cost systems for recording BC concentrations
Also, the regulatory station of NOA at Thissio has been integrated in the network of EMISSION, recording the concentrations of O3, NO2, CO, PM2.5 and BC, and located in an urban background area, representative of population exposure in the Central Sector of Athens.
The data from the monitoring sites are transmitted wirelessly via GSM/GPRS mobile and Wi-Fi networks to the EMISSION Data Management Center, where they are collected, validated, processed and then routed to the online visualization platform as well as to a mobile application, from where the measurement results are made available to stakeholders and the general public.
The platform, which is accessible through the EMISSION portal, is based on a Geographic Information System (GIS), which provides geospatial pollutant data from the monitoring sites displayed on a map of Attica. The assessment of pollution conditions is carried out through the Air Quality Index (AQI) of the European Environmental Agency (EEA), which provides verbal and color characterization pollutant levels.