Table 2.

Average concentrations and variations of air pollutants at different stations before and during lock in Barcelona, Spain (Tobías et al., 2020).

Type of station/air pollutant	Before lock	During lock	Variation
			μg/m3	(%)
Urban background
PM10	22.4	16.2	−6.2	−27.8
BC	1.1	0.6	−0.5	−45.4
NO2	30.0	15.9	−14.1	−47.0
SO2	1.2	1.0	−0.2	−19.4
O3	52.4	67.3	+14.9	+28.5
Traffic
PM10	29.2	20.2	−9.1	−31.0
NO2	42.4	20.6	−21.8	−51.4
SO2	2.5	2.6	+0.1	+1.8
O3	41.8	65.9	24.1	+57.7