Background: The new coronavirus disease COVID-19 began in December 2019 and has spread rapidly by human-to-human transmission. This study evaluated the transmissibility of the infectious disease and analyzed its association with temperature and humidity to study the propagation pattern of COVID-19. Methods: In this study, we revised the reported data in Wuhan based on several assumptions to estimate the actual number of confirmed cases considering that perhaps not all cases could be detected and reported in the complex situation there. Then we used the equation derived from the Susceptible-Exposed-Infectious-Recovered (SEIR) model to calculate R₀ from January 24, 2020 to February 13, 2020 in 11 major cities in China for comparison. With the calculation results, we conducted correlation analysis and regression analysis between R₀ and temperature and humidity for four major cities in China to see the association between the transmissibility of COVID-19 and the weather variables. Results: It was estimated that the cumulative number of confirmed cases had exceeded 45 000 by February 13, 2020 in Wuhan. The average R₀ in Wuhan was 2.7, significantly higher than those in other cities ranging from 1.8 to 2.4. The inflection points in the cities outside Hubei Province were between January 30, 2020 and February 3, 2020, while there had not been an obvious downward trend of R₀ in Wuhan. R₀ negatively correlated with both temperature and humidity, which was significant at the 0.01 level. Conclusions: The transmissibility of COVID-19 was strong and importance should be attached to the intervention of its transmission especially in Wuhan. According to the correlation between R₀ and weather, the spread of disease will be suppressed as the weather warms.

To investigate the fire behavior under low pressure, four configurations of cardboard box fires were comparatively tested in a sea-level city, Hefei, and a high-altitude city, Lhasa. During each test, mass burning rate, total heat release rate, multipoint flame temperature, and radiative heat flux were measured. From the experimental data, some specific fire behavior was observed that (1) the mass burning rate divided by fire base dimension can be correlated against the production of pressure-squared times length-cubed ( P² L³) to the power of 0.31, (2) the heat of combustion is lower in Lhasa probably due to the incomplete solid pyrolysis limited by oxygen, (3) the dimensionless plume temperature is correlated against the dimensionless flame height with a pressure term to the power of −2.0, and (4) the relative flame temperature estimated from the radiative heat flux indicated that the overall flame temperature is higher in Lhasa.

The ongoing novel coronavirus (COVID‐19) epidemic has evolved into a full range of challenges that the world is facing. Health and economic threats caused governments to take preventive measures against the spread of the disease. This study aims to provide a correlation analysis of the response measures adopted by countries and epidemic trends since the COVID‐19 outbreak. This analysis picks 13 countries for quantitative assessment. We select a trusted model to fit the epidemic trend curves in segments and catch the characteristics based on which we explore the key factors of COVID‐19 spread. This review generates a score table of government response measures according to the Likert scale. We use the Delphi method to obtain expert judgments about the government response in the Likert scale. Furthermore, we find a significant negative correlation between the epidemic trend characteristics and the government response measure scores given by experts through correlation analysis. More stringent government response measures correlate with fewer infections and fewer waves in the infection curves. Stringent government response measures curb the spread of COVID‐19, limit the number of total infectious cases, and reduce the time to peak of total cases. The clusters of the results categorize the countries into two specific groups. This study will improve our understanding of the prevention of COVID‐19 spread and government response.