Conclusion & Recommendations

We can conclude the following from our analysis:

China is a large country that is hugely populated, and the main reason for bad air quality. Since the government passed rules and regulations to control pollution, it has declined significantly the following years.
For long, people were under the impression that only urban areas were polluted but we know now that due to coal and wood burning, particles such as PM 2.5 count increased in the atmosphere which leads to health hazards.
The best air quality was experienced in the year 2020. Although the numbers in the analysis show it's 2021, we can only consider after the year ends.
Bad weather conditions, smog i.e., smoke with fog, burning of coal, industrial waste etc all contribute to China's polluted atmosphere.
We can see the air quality getting better steadily throughout the years but the best quality was experienced in 2020 possibly due to lockdowns and restrictions on public and private companies, transportation means, industries etc.
The SARS COVID-19 datasets were accumulative and needed to be resolved for our further analysis to accurate interpretation.
In Pearson and Spearman test, AQI and AQI Category was tested to be correlated with number of cases and deaths due to COVID for two cities ‘Beijing’ and ‘Shanghai’, and it was found out that only AQI and number of deaths have a very weak linear positive correlation in case of Beijing only.
However, on performing the linear regression test on AQI and number of deaths in Beijing, it was found that the two variables are having only spurious relationship.
For t-test, we have taken the mean of AQI of two cities ‘Beijing’ and ‘Shanghai’ and tried to find that whether the mean of AQI for these two cities are same, before and during lockdown. But it was found that the mean AQI of Beijing is higher that than of Shanghai both before and during lockdown.
For chi-square test, we tested the dependencies of number of confirmed COVID cases on AQI Categories by binning the number of cases to convert them into categorical data. The test was performed for Beijing and Shanghai separately. For Beijing the chi-square test was not valid as some of the groups of AQI categories has expected frequency less than 5. Thus, we grouped the AQI categories to get accurate and valid results from chi-square test.
From chi-square test, it was found that AQI Category and number of confirmed cases are independent of each other for both cities ‘Beijing’ and ‘Shanghai’.
Thus, we can conclude that COVID cases and deaths have no relationship with the air quality level of the country.

Our Recommendations include:

People in China could increase the usage of natural gas, solar energy, geothermal or water driven energy to replace coal consumption.
Installing electrical heating systems country wide as a mandatory set-up by the government can subsidize the installation fee and part of the utility fee.
Encourage the common public to take public transport to work, school etc or switch to options such as carpooling.
Government and NGOs should expand the project of clean energy vehicles which use naturally acquired and modified energy in place of burning fuel, gasoline, coal etc.
The government should enforce each province to submit an annual clean air action plan and set individual goals and targets for improving and in turn motivate them by a reward system eg: building more parks, schools or libraries etc.