  We investigate the relationship between synoptic/local meteorological
patterns and PM10 air pollution levels in the metropolitan area of Naples,
Italy. We found that severe air pollution crises occurred when the 850 and 500
hpa geopotential heights and their relative temperatures present maximum values
above the city. The most relevant synoptic parameter was the 850 hPa
geopotential height, which is located about 1500 m of altitude. We compared
local meteorological conditions (specifically wind stress, rain amount and
thermal inversion) against the urban air pollution levels from 2009 to 2013. We
found several empirical criteria for forecasting high daily PM10 air pollution
levels in Naples. Pollution crises occurred when (a) the wind stress was
between 1 and 2 m/s, (b) the thermal inversion between two strategic locations
was at least 3{\deg}C/200m and (c) it did not significantly rain for at least 7
days. Beside these meteorological conditions, severe pollution crises occurred
also during festivals when fireworks and bonfires are lighted, and during
anomalous breeze conditions and severe fire accidents. Finally, we propose a
basic model to predict PM10 concentration levels from local meteorological
conditions that can be easily forecast a few days in advance. The synthetic
PM10 record predicted by the model was found to correlate with the PM10
observations with a correlation coefficient close to 0.80 with a confidence
greater than 99%. The proposed model is expected to provide reliable
information to city officials to carry out practical strategies to mitigate air
pollution effects. Although the proposed model equation is calibrated on the
topographical and meteorological conditions of Naples, it should be easily
adaptable to alternative locations.
