List of abbreviations:
Arpae : Agency for Prevention, Environmental and Energy of Emilia-Romagna (Italy)
BC : Black carbon (PM chemical component)
C6H6 : Benzene (gaseous air pollutant)
COVID-19 : Coronavirus disease-2019
IOP : Intensive observation periods
Lockdown-1 : The first lockdown period in Italy from March 9th to May 3rd in 2020 and continued with less restrictions until the end of May
Lockdown-2 : The second (moderate) lockdown period in Italy from October 13th to the end of 2020 and continued in 2021 with restrictive measures varying according to the local trend of infections
NO2 : Nitrogen oxide (gaseous air pollutant)
O3 : Ozone (gas air pollutant)
PED : Pediatric Emergency Department
PM : Particulate matter
PM10 : Particulate matter smaller than 10 microns
PM2.5 : Particulate matter smaller than 2.5 microns
SARS-CoV-2 : Severe acute respiratory syndrome-coronavirus-2
SSOU : Short-stay clinical observation unit
TRAP : Traffic-related air pollution
TRAP contribution tracer: It represents the relative abundance of the mass fragment at m/z 57 over the total organic PM1 mass spectrum as measured by HR-ToF-AMS
WHO : World Health Organization