Air quality in the Greek city of Thessaloniki has worsened during the recent economic crisis, as residents burn more wood and other types of biomass to keep warm. A recent study has found a 30% increase in the concentration of fine particle (PM2.5) emissions associated with wood smoke from residential heating in 2012 and 2013, with implications for the health of local residents.
Thessaloniki is the second largest city in Greece and one of the most polluted cities in the EU with high levels of particulate matter (PM) in the air. Its economy has been damaged by the recent Greek financial crisis, and it is thought that more residents are heating their homes using wood and other biomass instead of more costly oil fuel.
To determine the extent to which wood burning has increased in Thessaloniki, the researchers took air samples during the winter months in 2012 (February-March) and 2013 (January-February). The samples were analysed for their chemical composition and toxicity to living cells in laboratory tests.
The results revealed there had been a substantial increase in fine particle emissions over the two years, with the total PM2.5 (particles smaller than 2.5 micrometres in diameter) increasing by 30% from 2012 to 2013, from 26 to 36 micrograms per cubic metre. Levels of PM2.5 were twice as high in the evenings compared with the mornings in 2013, illustrating the effects of higher wood smoke emissions from residential heating in the evening.
Organic matter was the most common component of the PM2.5 samples. Evening samples contained a higher proportion of organic matter (74%) compared with the morning samples (58%), again suggesting more wood and biomass were used for heating in the evening.
Potassium concentrations were two to three times higher in 2013 compared with 2012 and were also two to three times higher in the evening compared to the morning. Analysis revealed the potassium most likely came from wood smoke. Furthermore, the concentrations of vanadium and nickel, which indicate combustion of residential fuel oil and industrial activity, were 30-40% lower in 2013 compared with 2012.
The concentrations of the chemicals levoglucosan, mannosan, and galactosan, commonly found in wood smoke, were four to six times higher in 2013 compared with 2012 and the concentrations of all three compounds were three to four times higher in the evening compared with the morning.
The researchers also tested the effects of the PM2.5 samples on living cells and found that the levoglucosan, mannosan, galactosan and potassium components were all associated with increased ‘free radicals’. These have been linked to cell damage and health problems, such as inflammation of the lungs.
The authors of the study recommend urgent action by the authorities to implement air quality control strategies in the city. They suggest that one way to cut emissions would be to increase connections to natural gas supplies in residential areas.