Carbon dioxide in the urban area of Naples: Contribution and effects of the volcanic source

Naples is a large city located between two active volcanic areas: Campi Flegrei to the W and Vesuvius to the SE. The Solfatara crater, inside the caldera of the Campi Flegrei and nearest to the western quarters of the city, is a prodigious source of natural CO2 with a mean emission rate of 1067 ton/d, i.e. seven times higher than that of Vesuvius (151 ton/d). tudy shows that the area around the Solfatara and part of the urban area of Naples are affected by the volcanic plume when atmospheric circulatory patterns are dominated by the locally frequent sea breezes. Under these conditions the CO2 content in the air increases above normal values, reaching more than 1000 ppm in proximity to the Solfatara crater to a few tens of ppm several kilometres from the source. Although these values do not indicate a health risk even under the most unfavourable atmospheric conditions, the volcanic source contributes to the total CO2 burden from all urban emissions and hence to overall air quality. An emission rate ten times higher than the present one would lead to an air CO2 concentration in excess of recommended health protection thresholds.