Urban air quality changes resulting from the lockdown period due to the COVID-19 pandemic

This work aims to quantify potential pollution level changes in an urban environment (Madrid city, Spain) located in South Europe due to the lockdown measures for preventing the SARS-CoV-2 transmission. Polluting 11 species commonly monitored in urban zones were attended. Except for O(3), a prompt target pollutant levels abatement was reached, intensely when implanted stricter measures and moderately along those measures' relaxing period. In the case of TH and CH(4), it is evidenced a progressive diminution over the lockdown period. While the highest decreasing average changes relapsed on NOx (NO(2): − 40.0% and NO: − 33.3%) and VOCs (C(7)H(8): − 36.3% and C(6)H(6): − 32.8%), followed by SO(2) (− 27.0%), PM(10) (− 19.7%), CO (− 16.6%), CH(4) (− 14.7%), TH (− 11.6%) and PM(2.5) (− 10.1%), the O(3) level slightly raised 0.4%. These changes were consistently dependent on the measurement station location, emphasizing urban background zones for SO(2), CO, C(6)H(6), C(7)H(8), TH and CH(4), suburban zones for PM(2.5) and O(3), urban traffic sites for NO and PM(10), and keeping variations reasonably similar at all the stations in the case of NO(2). Those pollution changes were not translated in variations on geospatial pattern, except for NO, O(3) and SO(2). Although the researched urban atmosphere improvement was not attributable to meteorological conditions' variations, it was in line with the decline in traffic intensity. The evidenced outcomes might offer valuable clues to air quality managers in urban environments regarding decision-making in favor of applying punctual severe measures for quickly and considerably relieving polluting high load occurred in urban environments. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13762-022-04464-6.