| Summary: | Every day vast quantities of volatile organic compounds (VOCs) are emitted in the atmosphere from anthropogenic and natural sources. These compounds are the ‘fuel’ that promotes atmospheric photochemistry influencing the quality of ambient air locally, regionally and globally. Some of these compounds are considered dangerous for human health while others affect the climate due to their ability to form particles when they are oxidized.
In this study the organic emissions (gas and particulate) of several major sources of air pollution in Greece were characterized through laboratory experiments and field measurements. The emissions quantified included those from the burning of olive tree branches, from traffic, from biomass burning for residential heating, and from meat cooking. Our analysis indicates that the contribution of ‘traditional’ pollution sources such as transportation has decreased during the last two decades due to the control of their emissions and now other sources such as biomass burning or cooking are at least as important for organic pollutants in Greece.
The burning of olive tree branches is a common agricultural waste management technique after the pruning of olive trees during the months November to February. It is estimated that there are 125 million olive trees in Greece and that 6500 tones of fine particles are released in the atmosphere during these months. This number is a lot higher than the annual emissions from all the passenger cars in Greece (150 tones). In this study, the aerosol composition and the emission factors for particulate matter (PM) and VOCs were measured. These emission factors should be included in the relevant data bases concerning atmospheric pollution in Europe and they should be used in future atmospheric simulations. The chemical composition of the particles emitted during our experiments was similar to that determined by the analysis of the aerosol mass spectrometer (AMS) measurements confirming that the burning of olive tree branches is an important source during the winter in Greece.
The recent economic crisis in Greece had as a use of wood as fuel for residential heating. Measurements conducted in Athens during the winter of 2013 characterized the particulate and gas phase emissions from this practice. Aromatic VOCs such as benzene, toluene and the xylenes, were emitted from biomass burning in amounts similar to that from traffic. Moreover, several compounds that are associated mainly with biogenic sources, and are known to produce organic aerosol when oxidized, were also emitted. During summer, besides the emissions due to transportation in these urban environments, a large fraction of the VOCs was related to biogenic sources.
Emissions for cooking can contribute up to 30% of the organic aerosol in urban environments. In this study the fraction of the organic aerosol and organic vapors due to the charbroiling of meat in major Greek cities was estimated. Smog chamber experiments were used to characterize the composition of the aerosol and the VOCs that are emitted. Additionally the atmospheric chemical evolution of these emissions was examined by exposing them to sunlight and the typical oxidants of the atmosphere. Ambient measurements conducted in Athens and Patras during summer and winter as well as in Patras during Fat Thursday showed that the AMS spectra are significantly similar to those of the smog chamber experiments. The freshly emitted particles correspond more to the ambient winter measurements while the aged particles to the ambient summer measurements. The emissions from meat cooking are a significant source of organic aerosol in Greek cities and their chemical evolution needs to be accounted during source apportionment.
In the last phase of this work a new mobile dual smog chamber system was developed and tested. Our objective is to facilitate future source characterization and chemical aging studies moving the laboratory close to various pollution sources and certain environments that have been so far out of reach. The system was evaluated and was deployed in the field in order to assess its capabilities and limitations.
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