Background: Heat stress is considered one of the harmful factors in workplace environments, and prolonged exposure beyond recommended levels can adversely affect workers’ health. Various methods have been proposed to assess heat stress. Questionnaires are among the most important subjective tools, gaining popularity among researchers due to their ease of use and non-intrusiveness for workers. Nonetheless, a comprehensive questionnaire that covers all aspects of heat stress and is recognized as a standard tool by international organizations has not yet been fully established. This study aims to review existing questionnaires used to assess heat stress in workplace environments and compare their various dimensions from 2010 to 2022.
Methods: First, relevant keywords were extracted. Then, using the chosen search strategy, searches were conducted in the PubMed and Web of Science databases, considering inclusion and exclusion criteria. After thoroughly reviewing the extracted articles (448 in total), 11 articles were selected for final analysis
Results: The dimensions of “individuals’ perceptions of workplace environmental conditions” and “workload” were included in most studies (8 studies). In contrast, the dimension “availability of work guidelines in hot environments” was mentioned in only one study. Some questions were not categorized within the identified dimensions and were therefore grouped under a “miscellaneous” category.
Conclusion: The review of questionnaires revealed that none fully covered all aspects of heat stress in workplace environments, likely due to the multifactorial and complex nature of heat stress. These findings suggest a need for the development of a more comprehensive and standardized questionnaire to provide a complete assessment of heat stress.

Background: Absorption of low- to mid-frequency (LMF) noise has been challenging because of the inherently poor dissipation of classical noise-absorbing materials. For decades, the effective absorption of LMF noise has been an important topic and has attracted considerable interest from scientists in physics and engineering circles.

Method: This systematic review was conducted to assess the performance of LMF noise absorbers while considering influencing factors. Literature databases, including Scopus, Web of Science, IEEE, and Science Direct, were searched. In addition to the bibliographic sources, key publications and journal databases were searched from 2000 to 2022. Twenty studies were selected on the basis of the inclusion criteria. The data from the papers were analyzed via plot digitizer software.

Results: The results indicated that, with the exception of two factors resistivity and inner diameter the other factors positively affected the performance of low- to mid-frequency (between 40 and 1000 Hz) noise absorbers. With an increase in the number of layers, the absorption coefficient decreased by 0.06. In addition, increasing the surface porosity and thickness significantly increased the absorption coefficient at low to mid frequencies (0.16). By increasing the fiber gap, the absorption coefficient increased significantly by 0.06.

Conclusion: Among the various factors, the porosity, thickness, air gap, fiber gap, perforated plate, and mass had the most significant effects on the performance of the noise absorbers.