PM_(10) concentration levels at an urban and background site in Cyprus: The impact of urban sources and dust storms

摘要

Air quality in Cyprus is influenced by both local and transported pollution, including desert dust storms. We examined PM_(10) concentration data collected in Nicosia (urban representative) from April 1, 1993, through December 11, 2008, and in Ayia Marina (rural background representative) from January 1, 1999, through December 31, 2008. Measurements were conducted using a Tapered Element Oscillating Micro-balance (TEOM). PM_(10) concentrations, meteorological records, and satellite data were used to identify dust storm days. We investigated long-term trends using a Generalized Additive Model (GAM) after controlling for day of week, month, temperature, wind speed, and relative humidity. In Nicosia, annual PM_(10) concentrations ranged from 50.4 to 63.8 μg/m~3 and exceeded the EU annual standard limit enacted in 2005 of 40 μg/m~3 every year. A large, statistically significant impact of urban sources (defined as the difference between urban and background levels) was seen in Nicosia over the period 2000-2008, and was highest during traffic hours, weekdays, cold months, and low wind conditions. Our estimate of the mean (standard error) contribution of urban sources to the daily ambient PM_(10) was 24.0 (0.4) μg/m~3. The study of yearly trends showed that PM_(10) levels in Nicosia decreased from 59.4 μg/m~3 in 1993 to 49.0 μg/m~3 in 2008, probably in part as a result of traffic emission control policies in Cyprus. In Ayia Marina, annual concentrations ranged from 27.3 to 35.6 μg/m~3, and no obvious time trends were observed. The levels measured at the Cyprus background site are comparable to background concentrations reported in other Eastern Mediterranean countries. Average daily PM_(10) concentrations during desert dust storms were around 100 μg/m~3 since 2000 and much higher in earlier years. Despite the large impact of dust storms and their increasing frequency over time, dust storms were responsible for a small fraction of the exceedances of the daily PM_(10) limit. Implications: This paper examines PM_(10) concentrations in Nicosia, Cyprus, from 1993 to 2008. The decrease in PM_(10) levels in Nicosia suggests that the implementation of traffic emission control policies in Cyprus has been effective. However, particle levels still exceeded the European Union annual standard, and dust storms were responsible for a small fraction of the daily PM_(10) limit exceedances. Other natural particles that are not assessed in this study, such as resuspended soil and sea salt, may be responsible in part for the high particle levels.