Ozone over Mexico City during the COVID-19 pandemic

Abstract

During the COVID-19 pandemic lockdown, emissions of primary criteria pollutants in the Mexico City Metropolitan Area (MCMA) were substantially reduced, as in many other cities in the world. Unexpectedly, the daily average ozone concentration profile was practically indistinguishable from that of the past two years for the same time span in the calendar. So, we compared surface meteorology data, CO, NOx and O 3 hourly concentrations in the MCMA from the ozone season (from March 1 to May 31) for the years 2018, 2019, and 2020. Also, TROPOMI satellite data on column count of CO, NO 2 and HCHO, above a sparse grid of surface points in the MCMA, were also compared for March, April, and May 2020 with those from 2019. Population density used as a background variable to increase understanding of the observed differences allowed us to propose that reductions in NOx were so drastic that ozone formation moved rapidly from a VOC sensitive region towards a NOx sensitive region. The relevance of that unplanned policy provides impacts of contingent short-term emissions control actions during very high pollution episodes. Further analysis of these and other related data concerning VOC speciation and emissions patterns during the coronavirus lockdown may provide guidelines to enhance emission control policies in the post-COVID-19 times to come.

Nonlinear response of nitrate to NOx reduction in China during the COVID-19 pandemic

“…However, the O 3 concentration increased significantly (by ∼ 69%) due to the smaller titration of NO and the decrease of NO x in a VOC-limited environment. Previous studies also indicate that the changes in the VOCs composition due to amount use of disinfectants containing compounds such as alcohols and carbonyls may also play a role in O 3 increase ( Peralta et al, 2021 ). Besides, increased concentration of NH 3 was observed in Hebi and Nanjing, which might be contributed by rapid NO x emission reduction and the volatilization of NH 3 from the massive use of ammonia-based household cleaners during lockdown (discussed in Section 3.3 ).…”

The impact of coal combustion, nitrous oxide emissions, and traffic emissions on COVID-19 cases: a Markov-switching approach

“…Thus, the environmental impact of the COVID-19 pandemic found a significant positive on the air quality indicators across countries. Peralta et al ( 2021 ) argued that the Mexican government adopts strict measures to contain coronavirus pandemic that further control primary criterion air pollutants in a country. The country needs to adopt more sustainable healthcare policies to move forward towards green growth agenda in the long run.…”

Environmental management strategy in response to COVID-19 in China: Based on text mining of government open information

“…Ozone formation is driven by complex nonlinear photochemistry processes and is mainly controlled by VOC and NO x emissions. Peralta et al (2020) pointed out that the drastic reduction of NO x could be the main reason for O 3 increase. Controlling the tropospheric O 3 concentration has become a key task of “Battle for the blue sky”.…”