How to respond effectively to COVID-19? Reports based on environmental changes in Wuhan and Shanghai

The δ -variant of COVID-19 is blowing to globle economy, hummen’s life and health. The infection rates of δ -variant is twice of the original variants. It is putting the world in a harsher state. Lockdown policy is still powerful in stopping spread of virus. This paper aims to evaluate the lockdown impact on NO 2 , SO 2 , O 3 , PM 2.5 and PM 10 in Wuhan, which reported the rst OVID-19 infection case. We analyzed data of the whole periods including before, during and after blokade. Generally, lockdown has signicant decreasing effects on all the 5 pollutants except for surface ozone. The reasons for the pollutants’ changes are discussed from the aspects including social policy, people's living habits and Chinese character. To assess the extensive impact of lockdown policy on urban environment, we also studied the same pollutants in Shanghai, which is one of the biggest and central city in China and almost locates at the same latitude with Wuhan. Better results were obtained compared with those of Wuhan with all the pollutants decreasing their concentration and a better air quality. This effects even last after the blockade. This is mainly because Shanghainese have formed more prudent living habits and attach more importance to environmental protection during the lockdown period. Althgough COVID-19 brings bad effect on globle socio-economy and humen’s health, people get chance to rethink the value of life: We should sustainablely develop and pursuing spiritual instead of excessive material enjoyment. It can sustain a healthy living enviroment.


Introduction
Wuhan (113°41′-115°05′E, 29°58′-31°22′N) is the capital of Hubei Province with an area of 8,467 k 2 and a population of 11.21 million in 2019 (https://baike.so.com/doc/498920-528228.html). As a megacity in the middle and lower reaches of the Yangtze River, Wuhan is the largest metropolis in Chinese central part and one of the seven central cities in China. It is important industrial, science and education bases; and also a comprehensive transportation hub in China. Wuhan is rich in freshwater. It accounts for about a quarter of Wuhan's urban area and is known as the thoroughfare of nine provinces. Besides the Yangtze River and the Hanshui River, which run through the city and divide it into three parts. i.e., Wuchang, Hankou and Hanyang, there are dozens of fresh water lakes. Duirng them, Tangsun Lake is the largest urban lake in Asia (https://baike.so.com/doc/498920-528228.html). There are lots of studies on air pollutants during the COVID-19 period (Huang et al 2020; Sicard et al 2020; Zhang 2020; Zhu 2020; Maet al 2021; Su 2021). These studies usually refer levels of major pollutants during the lockdown period and comprehensive analysis before, during and post-lockdown are yet to be available (Haug 2020). As Wuhan reported the rst global COVID-19 case and had the longest lockdown time in China (Zheng 2020). It offered an optimal chance to study the air pollutants' changes and quality before, during and after the blockades. We studied ve major air pollutants in Wuhan, i.e., January to 25th March in Wuhan. In order to deeply study the lockdown policy on enviroment, data of the same pollutants in Shanghai (120°52′-122°12′ E, 30°40′-31°53′ N), which is just east to Wuhan and one of the largest central city of China, were used to make a comparison. Besides, the corresponding average data of year 2018 to 2019 were also compared. They are general cases from human interfernce. This study nont only lls the blank of air quality comparison before, during and after the lockdown periods; but also provides discussion between economic growth and enviromental protection. Besides, We also discuss powerful ways to contral the outbreak.  values, respectively, before, during and after the lockdown period in year 2020. Comparatively, there are only 68 values from Shanghai. So, the dataset from Wuhan is greater than the one from Shanghai, which had a shorter lockdown period.

Data Processing
Two comparisons were done: First, comparison before lockdown period (1st Jan-23rd Jan) and during lockdown period (24th Jan − 9th Feb) in year of 2020. Second, comparison data from the same dates but of different years (average data of 2018-2019 and data of 2020). One-way ANOVA, Nonmetric Multidimensional scaling (NMDS) analysis and cluster analysis were used to process the data. SPSS (SPSS Inc., Chicago, USA) was used to do one-way ANOVA; whereas R were used to do cluster analysis (version 3.4.1). The calculation of the Air Quality Sub-Index (AQI) for Air Pollutant (IAQIP) measures the total quality of air are as followed: AQI = max(I 1 , I 2 , …, L n ) ;IAQI P = I high − I low C high − C low C P − C low + I low the concentration of pollutant p; the concentration breakpoint that is ≤ C high : the concentration breakpoint that is ≥ C P ; I low : the index breakpoint corresponding to C low ; I high : the index breakpoint corresponding to C high .

Concentration changes of major pollutants in wuhan before and duiring the Covid-19 lockdown periods in year 2020
Generally, concentrations were in order of PM 2.5 > PM 10 > NO 2 > O 3 > SO 2 ( Fig. 2 and Fig. 3). PM 2.5 , PM 10 , NO 2 had similar changing trends (Fig. 2), which is almost opposite to the trend of O 3 . (Fig. 3). The concentrations of SO 2 were relatively steady with similar changing trand of surface O 3 ( Fig. 2 and Fig. 3).
Little peeks appeared during the late time of the Chinese Spring Festival (Fig. 2). That may be because of Lockdown peiriod has great positive effects on the AQI (Fig. 5), However, AQI increased again when the city was unlockdown, that mainly because the recovery of tra c and reopen of some heavy industries.

Comparisons between COVID-19 and non-COVID-19 periods
All pollutants varied dramatically in 2020 compared with the same period in 2018 and 2019, especially during the COVID-19 lockdown period (Fig. 6). The average decreasing rate of SO 2 , NO 2 , PM 2.5, PM 10, and O 3 were 19%, 46%, 32%, 23% and − 26%, respectively, before and duiring the lockdown periods. So, the lockdown policy indeed altered all the pollutant concentrations. Concenquently, closing factories and reducing usage of motor vehicles are effective ways to control most pollutants except for O 3 .

Concentrations of the ve major pollutants in Shanghai as a comparison
Similar but did not like Wuhan (Fig. 2), all the ve major pollutants signi cantly decreased in Shanghai (p < 0.001) during the blockade compared with their respective concentrations before the lockdown peiriod.
Only very signi cant negtive correlation were found between O 3 and NO 2 (p = -0.025) (Fig. 7). Cluster analysis and NMDS (Fig. 8) shows that PM 2.5 , PM 10, NO 2 and O 3 had similar sources and SO 2 had relative independent source. This is similar with the results of Wuhan. Lockdown peiriod also had positive effects on AQI in Shanghai (Fig. 9), and the effect is much greater than that on Wuhan (Fig. 5) because it shows decrease not only on O 3 concentration but also continously on AQI after the blockade.
All pollutants decreased dramatically in 2020 compared with the same period in 2018 and 2019 in Shanghai (Fig. 10)    Comparatively, Shanghai did better in controling all the ve air pollutants, which sharply decreased compared with those in Wuhan ( Fig. 3 and Fig. 6). It's worth noting that O 3 also showed a decreasing rate Generally, the controlling of air major pollutants in Wuhan cannot be lasted for long when the city was unlocked re ected by the increasing AQI (Fig. 5). Comparatively, AQI in Shanghai was even lower after the city blockade (Fig. 9). This is related with residents' living habits. It seems that residents in Shanghai don't like parties very much, and they pay more attention to protecting the natral environment. Their living habbit are more independent and rigorous. This conforms to the characteristics of metropolises in developed countries. So, although Shanghai is an international transportation hub, it has a very high level of infection control and maintain low infection rate of Covid-19 variants (China Statistics Bureau 2021) along with high vaccination rate and control of heavy industry until now. Although the 5 major pollutants' concentration in year 2018-2019 of Shanghai were much higher than the relative values in Wuhan, the decreasing rates of Shanghai were also much higher than those in wuhan during the blockade. This shows that Shanghai has stronger and more effective virus control measures.

Conclusion
Covid-19 is still bring serious effect on humen's world, especially with the explosure of δ-, λ-and γ-variant. Lockdown is proved to be effective in stopping spread of virus. Shanghai always does a good job, which is much better than most cities in the world. Good living habbits, cautious attitudes and powerful executive force are the effective ways. As the only economic positive growth contry in the world in year 2020, China has been taking six effective measures, including stopping non-necessary tra c and face to face communications, timely nucleic acid testing and isolations, wearing masks, strict disinfections, using public chopsticks, uniting against the epidemic in the whole contry, and providing free vaccination with the biggest efforts. Lockdown policy works well in promopting the air qualities, no matter in Wuhan, Shanghai or other cities in the world. Shanghai really does a good job in all aspects including stopping the spread of COVlD-19 and its variants, protecting enviroment and promopting economy. As the city reporting the rst COVlD-19 infection case, Wuhan experinced the most severe outbreak and combatting, but it survived and provided a good opportunity for environmental research before, during and after the lockdown periods.  Figure 1 Sampling locations of the ve major air pollutants: NO2, SO2, O3, PM2.5 and PM10 Figure 2 Loading [MathJax]/jax/output/CommonHTML/jax.js Changes of major pollutants from 1st Jan to 25th Mar with lockdown beginning date of 23rd Jan in Wuhan