Table 2.

Relative percentage change in OMI NO₂ during 2018–2020. (where: 2020/2019 is ratio of 2020 vs 2019, 2020/2018 is ratio of 2020 vs 2018).

	2020 vs 2019				2020 vs 2018
	Period 1	Period 2	Period 3	Period 4	Period 1	Period 2	Period 3	Period 4
Warsaw	5.8	−5.1	9.2	−110.5	−30.8	−62.2	2.1	−78.9
Gdansk	−76.5	−18	−25.8	−18.8	−82.4	−13	−35.5	−18.8
Lodz	50.6	−16.2	−4.8	−25	19	−161.3	−45.2	−7.1
Krakow	−8.3	−45.8	−35.6	−13.2	6.7	−10.4	−37.8	−7.4
Poznan	26.4	39.5	−100	−60	26.4	11.6	−186.7	−153.3
Wroclaw	−2.8	−3.5	−30	−13	3.9	12.3	−70	−4.3