摘要:

IntroductionOver the past few decades, agencies responsible for evaluating the levels of pollution and air quality in the most industrialised countries have proposed indices that will provide assessments of a more global nature. Among the first indices used were the PINDEX (Pollutant Index), established by the Environmental Protection Agency (EPA), ORAQI (Oak Ridge Air Quality Index),1,2(which were adopted internationally by different countries), MAQI (Mitre Air Quality Index), MURC, IMEXCA and IMECA, STARAQS, ICAIRE,etc., although these have a more local, or at most national, character. Indices that describe air quality at shorter-term are the PSI (Pollutant Standard Index) and the AQI (Air Quality Index)3,4used by the EPA and based on reference values or maximum hourly values fixed by the legislation the USA, the NAAQS (National Ambient Air Quality Standards)5or the EVI (Extreme Values Index).One of the most accredited and internationally accepted indices and most used to assess air quality, considering the situation of different pollutants simultaneously, is the ORAQI. Starting from data recorded at the four air quality monitoring stations in the city of Salamanca over the 1993–2001 period, here we calculated this global air quality index for each of the areas in which the stations are located.Most of the city of Salamanca is situated on the right bank of the River Tormes and is spread over almost 50 km2. The standard coordinates of the city are 5° 41′ W 40° 58′ N, at an altitude of 808 m a.s.l., with a maximum difference in altitude of 40 m. In view of its geographic situation, the characteristics of the surrounding terrain, and its altitude, the climate of Salamanca is continental, due to the proximity of the Atlantic Ocean, although this is attenuated by the relief. The climate is dry, the warmest month being July, with a mean temperature of 21.9 °C, and the coldest one January, with 3.4 °C. Thus, in accordance with the climatic classification based on temperature (and given that the difference between the mean temperature of the hottest month and that of the coldest month is almost 20 °C), the climate of the city can be characterised as between moderate and extreme.Precipitation in the city is low, around 400 mm year−1; April and May show the highest levels, followed by October, while the driest months are usually August and November, followed in this sense by July and March. In general winds are weak; the highest annual and monthly frequencies of wind direction correspond to the SW, followed by the NE and W.

ISSN:1464-0325    

DOI:10.1039/b302664g

出版商:RSC    

年代:2003

数据来源: RSC