Safety Performance Assessment of Construction Sites under the Influence of Psychological Factors: An Analysis Based on the Extension Cloud Model.

Psychological hazards within organizational structures of construction sites are difficult to detect and can have significant negative impacts on safety performances when such hazards erupt. At present, most safety performance assessment models for construction sites ignore psychological factors. Therefore, in order to reveal psychological hazards within construction site organizations and to avoid damage caused by psychological hazards to safety performances, this paper evaluates the safety performances of construction sites by focusing on leader-member exchange ambivalence as the main trigger point. The evaluation system and evaluation criteria are established through three aspects: building scale, emotional orientation, and stability factors. The hierarchical analysis method, game theory, and extension cloud model are combined to make evaluation results more objective and credible. Moreover, a construction project with high technical requirements, high investment, and complex construction conditions (defined as a complex project) and an ordinary construction project with low technical difficulty and simple construction conditions (defined as a general project) were selected for analysis. The evaluation results indicate that both complex projects and general projects have safety hazards regarding psychological orientations. Finally, this paper makes some suggestions from three aspects: management system and corporate culture, building site intelligence, and social opinion to improve the safety performances of construction sites. The evaluation results are the same as actual operation results, which verify that models proposed in this paper can be used for safety performance evaluations of actual construction projects and provide help for managers to grasp overall safety levels.

Mass SARS-CoV-2 molecular and serological screening of medical staff and patients in Hangzhou, China: no evidence of RNA detection, low seroprevalence, and limited exposure risk in the hospital setting.

BACKGROUND: To assess and limit the SARS-CoV-2 exposure risk from symptomless individuals in the hospital setting, molecular and serological screening of staff and patients attending a tertiary hospital in China was conducted. METHODS: SARS-CoV-2 RNA was tested by quantitative RT-PCR. Anti-SARS-CoV-2 IgM and IgG were screened initially with two lateral flow immunoassays (LFIs) and further confirmed with three chemiluminescence immunoassays (CLIAs). The assay performance was assessed using archived samples from 32 confirmed COVID-19 cases and 80 healthy individuals. RESULTS: Between April 24 and May 8, 2020, 16,043 subjects (7,392 medical staff, 4,714 inpatients, 1,209 chaperones, 1,705 outpatients, and 1,023 fever clinic patients) were screened. No subject tested positive for viral RNA. Seventy-three (0.46%) tested positive for IgM or IgG on the initial LFI screening, of whom 63 were investigated with CLIAs: 2 (0.01%) were confirmed as seroreactive and 18 (0.11%) were indeterminate. Unconfirmed seroreactivity was significantly more frequent in fever clinic patients. The CLIAs showed similar (95.0-100%) IgM or IgG specificity but higher IgG sensitivity (93.75-96.88% vs. 31.25-81.25%) than the LFIs. The confirmed seropositive cases included a previously discharged COVID-19 patient and an undiagnosed symptomless patient showing detectable IgM and IgG over 35 days of follow-up. No transmission was evidenced within the corresponding family cluster. CONCLUSIONS: Low SARS-CoV-2 prevalence and limited exposure risk were observed. Seroprevalence varied between 0.012% and 0.12% according to the testing algorithm and the confirmation criteria used, indicating that quality standards for serological tests are needed. Protective immunity in asymptomatic COVID-19 patients who recovered needs to be investigated further, but the associated risk of transmission appeared limited.