Decisive role of ozone formation control in winter PM2.5 mitigation in Shenzhen, China.

During the COVID-19 lockdown, atmospheric PM2.5 in the Pearl River Delta (PRD) showed the highest reduction in China, but the reasons, being a critical question for future air quality policy design, are not yet clear. In this study, we analyzed the relationships among gaseous precursors, secondary aerosols and atmospheric oxidation capacity in Shenzhen, a megacity in the PRD, during the lockdown period in 2020 and the same period in 2021. The comprehensive observational datasets showed large lockdown declines in all primary and secondary pollutants (including O3). We found that, however, the daytime concentrations of secondary aerosols during the lockdown period and normal period were rather similar when the corresponding odd oxygen (Ox≡O3+NO2, an indicator of photochemical processing avoiding the titration effect of O3 by freshly emitted NO) were at similar levels. Therefore, reduced Ox, rather than the large reduction in precursors, was a direct driver to achieve the decline in secondary aerosols. Moreover, Ox was also found to determine the spatial distribution of intercity PM2.5 levels in winter PRD. Thus, an effective strategy for winter PM2.5 mitigation should emphasize on control of winter O3 formation in the PRD and other regions with similar conditions.

Analysis of influencing factors related to elevated serum troponin I level for COVID-19 patients in Yichang, China.

BACKGROUND: Cardiac injury is a common condition among hospitalized coronavirus disease 2019 (COVID-19) patients, and is associated with a higher risk of mortality. However, the mechanism of myocardial injury in COVID-19 remains unclear. In this retrospective study, we compared the clinical characteristics of COVID-19 patients with different troponin I (TnI) levels during hospitalization to provide a clinical reference for the identification of those at high-risk. METHODS: In total, 218 patients diagnosed with COVID-19 in Yichang Central People's Hospital and Yichang Third People's Hospital between January 23 and February 19, 2020 were initially included. Of these patients, 89 underwent TnI testing during hospitalization and were finally included in the study. The medical history, clinical signs and symptoms at the time of admission, and laboratory test results were recorded. The patients were assigned to the normal TnI group (TnI <0.01 µg/L; n=67) or the elevated TnI group (TnI >0.01 µg/L; n=22). RESULTS: The incidence of elevated TnI in our patient cohort was 24.7%. There were significant differences between the two groups in the following factors: history of coronary heart disease (CHD), age, lymphocyte count, prothrombin time (PT), activated partial thromboplastin time (APTT), and levels of interleukin (IL)-6, C-reactive protein (CRP), myoglobin (MYO), lactate dehydrogenase (LDH), and albumin (all P<0.05). Binary logistic analysis showed that a history of CHD, age, lymphocyte count, IL-6, APTT, and MYO were influencing factors of elevated serum TnI. CONCLUSIONS: A history of CHD, advanced age, decreased lymphocyte count, increased IL-6, increased MYO, and prolonged APTT were independent influencing factors of elevated TnI in COVID-19 patients. COVID-19 patients with these characteristics are prone to myocardial injury.