Table 1.

Variable description and descriptive statistics.

Variable	Min	Max	Mean	SD	Description	Source
$\ln GD{P}_i$	6.633	11.678	9.455	1.135	Gross Domestic Product per capita (current USD)	https://m.statisticstimes.com/economy/countries-by-projected-gdp-capita
$\ln P{M}_i$	2.292	4.593	3.691	0.506	Average PM2.5 concentration (µg/m³)	https://statisticstimes.com/economy
$\ln Po{p}_i$	0.746	9.030	4.323	1.364	Population density (people per km2)	https://knoema.com
$\ln COVI{D}_i$	4.158	11.978	9.541	1.805	The number of COVID-19 confirmed cases (ratio with population). This variable can be viewed as COVID-19 incidence rate.	https://www.worldometers.info/coronavirus/
$\ln Tem{p}_i$	−0.400	3.361	2.772	0.713	Average temperature (Celsius)	https://www.weather-atlas.com/
$\ln Loc{k}_i$	0.000	5.192	3.700	0.913	Number of days in lockdown per year (Day)	https://graphics.reuters.com/world-coronavirus
$\ln Inde{x}_i$	3.060	4.542	3.948	0.269	COVID-19 Recovery Index, which measures country’s success in treating patients that have been diagnosed COVID-19 positive	Global Infection Trend—Fu
$\ln Ope{n}_i$	−4.605	5.501	−0.879	1.630	Trade openness (Ratio with GDP)	https://countryeconomy.com/trade
$\ln r_i$	−2.302	4.071	0.964	1.270	Real interest rate (%)	https://tradingeconomics.com/country-list/interest-rate
$\ln FD{I}_i$	−1.840	18.757	6.512	3.108	Foreign direct investment (Million USD)	https://tradingeconomics.com/country-list/foreign-direct-investment

Note: The data is accessed on 9 March 2022.