ABSTRACT
With rapid economic development and industrialization, the construction industry continues to rank among the most hazardous industries in the world. Therefore, construction safety is always a significant concern for both practitioners and researchers. The objective of this study was to create a structural modeling of components that influence the safety performance in construction projects. We followed a two-stage Structural Equation Model based on a questionnaire study [n=230]. In the first stage, we applied the Structural Equation Model to the proposed model to test the validity of the observed variables of each latent variable. In the next stage, we modified the proposed model. The LISREL 8.8 software was used to conduct the analysis of the structural model. A good-fit structural model [Goodness of Fit Index=0.92; Root Mean Square Residual=0.04; Root Mean Square Error of Approximation=0.04; Comparative Fit Index=0.98; Normalized Fit Index=0.96] indicated that social and organizational constructs influence safety performance via the general component of the safety climate. The new structural model can be used to provide better understanding of the links between safety performance indicators and contributing components, and make stronger recommendations for effective intervention in construction projects
ABSTRACT
There can be little doubt that the construction is the most hazardous in-dustry in the worldwide. This study was designed to modeling the factors affecting un-safe behavior from the perspective of safety supervisors. The qualitative research was conducted to extract a conceptual model. A structural model was then developed based on a questionnaire survey [n=266] by two stage Structural Equation Model [SEM] approach. An excellent confirmed 12-factors structure explained about 62% of variances unsafe behavior in the construction industry. A good fit structural model indicated that safety climate factors were positively correlated with safety individual factors [P<0.001] and workplace safety condition [P<0.001]. The workplace safety condition was found to play a strong mediating role in linking the safety climate and construction workers' en-gagement in safe or unsafe behavior. In order to improve construction safety performance, more focus on the workplace condition is required.
ABSTRACT
Formaldehyde [FA], one of the simplest organic molecules, is a flammable, pungent, irritating and colorless gas. This study aimed to investigate the effects of various concentrations of FA vapor on sperm parameters and testicular tissue. In this experimental study, we randomly assigned 36 adult male mice to one control and two experimental groups [n=12 for each group]. The control group [C] did not receive FA. Group F1 [low concentration] was exposed to 10 ppm FA vapor and the F2 [high concentration] group was exposed to 20 ppm FA vapor. FA was administered for ten days, eight hours per day for both groups. At the end of the exposure period, half of the animals in each group were sacrificed 24 hours after exposure to detect any short-term effects; the rest of the mice were sacrificed 35 days later to assess for long-term effects. Sperm parameters were analyzed by Computer-assisted Sperm Analyzer [CASA] and histological changes determined. In addition, we studied changes in testosterone hormone. Data were analyzed by one-way ANOVA followed by the Scheffe test using SPSS software. Long-term effects of FA in the experimental groups included significant reductions in sperm cell numbers and sperm viability. A drastic reduction in progressive motility and increased abnormal sperm percentage [p<0.001] compared with the control group was also noted. Histological study of testes specimens in the experimental group revealed displacement of germinal cells, along with degeneration of Leydig cells and seminiferous tubules. Exposure to FA vapor can destroy testicular structure and decrease percentages of concentration, viability, normal morphology, and progressive motility, in addition to increasing the percentage of immotile sperm