Objective To know the contamination situation of the centralized air conditioning-ventilating systems in hotels in Shenzhen City, Guangzhou province and to ensure the indoor air quality when the centralized air conditioning-ventilating systems were at working. Methods 22 hotels were selected to determine the total count of bacteria and fungi in internal surface of pipes and air blow, the dust volume of internal surfaces of pipes, inhalable particulate matter(PM10) in air blow, and Legionellae in cooling tower water. Results The eligibility percent of dust volume, the total number of bacteria and fungi in internal surface was 94.76 %, 95.71% and 91.90 % respectively,the eligibility percent of PM10, the total count of bacteria and fungi in air blow was 42.54%, 94.76% and 84.29% respectively, and the detected rate of Legionellae was 57.50%. Conclusion The pollution in some degrees has been observed in the centralized air conditioning-ventilating systems in hotels of Shenzhen City, so it is considered as the important measure to improve indoor air quality and ensure people health to strengthen management of centralized air conditioning-ventilating systems in the usage.

Objective To assess the association between the concentration of the air pollutant PM2.5 and daily outpatient visits for respiratory disease. Methods All records of daily outpatient visits to three hospitals in Shenzhen from January 1 to December 31, 2013 were collected. Daily air pollution monitoring and meteorology data from the same period were also collected in Shenzhen. The data were analyzed using a semiparametric generalized additive model with Poisson distribution of time series analysis controlling for long-term and seasonal trends, flu, DOW, public holidays, and meteorological factors. The excess risk (ER) of respiratory disease and its 95%CI value were calculated, along with the incremental increase of 10 μg/m3 in PM2.5 concentration. Results Number of outpatient visits for respiratory diseases totaled 1 428 672 (daily range:1 790-5 228). The annual average PM2.5 concentration was 40.2μg/m3 (daily range:7.2-137.1μg/m3). The lag1 factor had the most significant impact on the lag effect. We estimated that a 10 μg/m3 increase in day-before PM2.5 concentration was associated with a 1.809% (95% CI:1.709%-1.909%) ER of visits for respiratory disease. After controlling for other pollutants (NO2, CO, and O3), the effect remained stable. When NO2, CO, and O3 were introduced separately, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of daily outpatient visits for respiratory disease was 1.814% (95% CI:1.706%-1.923%), 2.780% (95% CI: 2.668%-2.892%), and 1.513% (95% CI: 1.403%-1.624%), respectively. With simultaneous control of NO2 and O3, NO2 and CO, and CO and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 1.369% (95% CI: 1.242%-1.497%), 2.709% (95% CI: 2.590%- 2.828% ), and 2.577% (95% CI: 2.452%- 2.702% ), respectively. With simultaneous control of NO2, CO, and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 2.370% (95% CI: 2.231%-2.509%). Conclusions PM2.5 can increase the risk of outpatient visits for respiratory disease in Shenzhen.

Objective To assess the association between the concentration of the air pollutant PM2.5 and daily outpatient visits for respiratory disease. Methods All records of daily outpatient visits to three hospitals in Shenzhen from January 1 to December 31, 2013 were collected. Daily air pollution monitoring and meteorology data from the same period were also collected in Shenzhen. The data were analyzed using a semiparametric generalized additive model with Poisson distribution of time series analysis controlling for long-term and seasonal trends, flu, DOW, public holidays, and meteorological factors. The excess risk (ER) of respiratory disease and its 95%CI value were calculated, along with the incremental increase of 10 μg/m3 in PM2.5 concentration. Results Number of outpatient visits for respiratory diseases totaled 1 428 672 (daily range:1 790-5 228). The annual average PM2.5 concentration was 40.2μg/m3 (daily range:7.2-137.1μg/m3). The lag1 factor had the most significant impact on the lag effect. We estimated that a 10 μg/m3 increase in day-before PM2.5 concentration was associated with a 1.809% (95% CI:1.709%-1.909%) ER of visits for respiratory disease. After controlling for other pollutants (NO2, CO, and O3), the effect remained stable. When NO2, CO, and O3 were introduced separately, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of daily outpatient visits for respiratory disease was 1.814% (95% CI:1.706%-1.923%), 2.780% (95% CI: 2.668%-2.892%), and 1.513% (95% CI: 1.403%-1.624%), respectively. With simultaneous control of NO2 and O3, NO2 and CO, and CO and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 1.369% (95% CI: 1.242%-1.497%), 2.709% (95% CI: 2.590%- 2.828% ), and 2.577% (95% CI: 2.452%- 2.702% ), respectively. With simultaneous control of NO2, CO, and O3, for every 10μg/m3 rise in PM2.5 concentration, the excess risk of respiratory disease was 2.370% (95% CI: 2.231%-2.509%). Conclusions PM2.5 can increase the risk of outpatient visits for respiratory disease in Shenzhen.

Objectives:This study aimed to evaluate the effect of the strategies on COVID-19 outbreak control in Shenzhen, and to clarify the feasibility of these strategies in metropolitans that have high population density and strong mobility.Methods:The epidemic feature of COVID-19 was described by different phases and was used to observe the effectiveness of intervention. Hierarchical spot map was drawn to clarify the distribution and transmission risk of infection sources at different time points. The Susceptible-Exposed-Infectious-Asymptomatic-Recovered model was established to estimate case numbers without intervention and compare with the actual number of cases to determine the effect of intervention. The positive rate of the nucleic acid test was used to reflect the risk of human exposure. A survey on COVID-19 related knowledge, attitude and behaviors were used to estimate the abilities of personal protection and emergency response.Results:The epidemic of COVID-19 in Shenzhen experienced the rising, plateau and decline stage. The case number increased rapidly at the beginning, with short duration of peak period. Although the epidemic curve showed human-to-human transmission, the "trailing" was not obvious. From the spot map, during the intervention period, the source of infection was widely distributed. More cases and higher transmission risk were observed in areas with higher population density. After the effective intervention measures, both infection sources and the risk of transmission decreased. After compared with the estimated case numbers without intervention, actual number proved the COVID-19 control strategies were effective. The positive rate of nucleic acid test for high risk populations decreased and no new cases reported since February 16. Shenzhen citizens had high knowledge, attitude and behavior level, and high protection ability and emergency response.Conclusions:Although the response initiated by the health administration department played a key role at the early stage of the epidemic, it was not enough to contain the outbreak of COVID-19. The first-level emergency response initiated by provincial and municipal government was effective and ensured the start of work resumption after the Spring Festival. Metropolitans like Shenzhen can also achieve the goals of strategies and measures for containment and mitigation of COVID-19.