Assessing air quality changes in large cities during COVID-19 lockdowns: The impacts of traffic-free urban conditions in Almaty, Kazakhstan
Autor
Kerimray, Aiymgul
Baimatova, Nassiba
Ibragimova, Olga P.
Bukenov, Bauyrzhan
Kenessov, Bulat
Plotitsyn, Pavel
Karaca, Ferhat
Institución
Resumen
Number of cities worlwide experienced air quality improvements during COVID-19 lockdowns; however,
such changes may have been different in places with major contributions from nontraffic related sources.
In Almaty, a city-scale quarantine came into force on March 19, 2020, which was a week after the first
COVID-19 case was registered in Kazakhstan. This study aims to analyze the effect of the lockdown from
March 19 to April 14, 2020 (27 days), on the concentrations of air pollutants in Almaty. Daily concentrations
of PM2.5, NO2, SO2, CO, O3, and BTEX were compared between the periods before and during the lockdown.
During the lockdown, the PM2.5 concentration was reduced by 21% with spatial variations of 6–34% compared to the average on the same days in 2018–2019, and still, it exceeded WHO daily limit values for
18 days. There were also substantial reductions in CO and NO2 concentrations by 49% and 35%, respectively,
but an increase in O3 levels by 15% compared to the prior 17 days before the lockdown. The concentrations
of benzene and toluene were 2–3 times higher than those during in the same seasons of 2015–2019. The
temporal reductions may not be directly attributed to the lockdown due to favorable meteorological variations during the period, but the spatial effects of the quarantine on the pollution levels are evidenced. The
results demonstrate the impact of traffic on the complex nature of air pollution in Almaty, which is substantially contributed by various nontraffic related sources, mainly coal-fired combined heat and power plants and household heating systems, as well as possible small irregular sources such as garbage burning and
bathhouses.