Indoor Air

Measuring the systemic impact of major public health emergencies on the light industry and preventing various uncertain future external risks have become the key challenges to ensuring the stability of the light industry. This paper takes the occurrence of major public health emergencies as the background and focuses on environmental issues such as air pollution and indoor air quality degradation during emergencies. And to explore the multiscale impact of major public health emergencies on the light industry, typical light industry subsectors, and light industry enterprises. The findings of our study reveal that major public health emergencies have a negative impact on the light industry, particularly in the form of a short-term decline in exports, which tends to converge in the long run. Further, it is also revealed that there is heterogeneity in the impact on environmentally sensitive industries, labor-intensive industries, and others. At the microfirm level, major public health emergencies have shown a negative effect, especially the recent pandemic, which has a longer duration and a wider reach. Through multiscale research, this paper provides policy suggestions to improve the macrogovernance mechanism and risk prevention system for the light industry.

The risks to human health posed by airborne pathogens can be mitigated by the use of ultraviolet-C (UV-C) radiation. In general, UV-C-based systems should be applied in a manner that allows effective inactivation of airborne pathogens, while controlling human exposure to below defined limits. Among the methods used to apply UV-C radiation in indoor settings to meet these objectives are UV-C-based air cleaners. These devices can be effective for the control of airborne pathogens, but methods are needed to quantify and validate their performance. To address this need, an experiment-based method and a mathematical model were developed to quantify the effects of UV-C-based air cleaners on the concentration of an aerosolized, viral challenge agent. The method and model were demonstrated to allow quantification of disinfection efficacy and to allow translation of the results from the test environment to the application environment. The primary figure-of-merit from these tests was the clean air delivery rate (CADR), which is commonly used to characterize the disinfection efficacy of these devices. The ability of a validated air cleaner to improve indoor air quality in application settings is simulated based on the measured value of CADR from laboratory tests and the mathematical model.

The indoor living environment of residential buildings is an important part of the habitat environment, affecting the living experience and well-being of the residents, which in turn influences the price of housing. However, few existing studies systematically concentrate on the integrated influence of the various elements of the indoor living environment on prices, and even fewer analyze the relationship between the indoor living environment and housing prices of different houses within the same residential quarter from a microperspective. Therefore, we use the Taojinjiayuan Residential Quarter, located in central Guangzhou City, China, as a case study area and analyze the extent and direction of the effect of the indoor living environment on housing prices. The study found that the quantitative evaluation results of the indoor living environment were reasonable. The integrated indoor living environment factors are closely related to housing prices. Orientation, view, and acoustic environment are significantly and positively related to housing prices, which have a different intensity of influence. These findings are beneficial to real estate developers, building designers, and residential users in quantitatively understanding the value of the indoor living environment.

Organic films act as passive air samplers and can be employed to assess the concentration of semivolatile organic compounds (SVOCs), such as phthalates, in the gas phase over a defined period using the kinetic adsorption model. Consequently, indoor organic films have been identified as effective media for evaluating human exposure to SVOCs. This study proposed an organic film-based method for assessing SVOC exposure in the indoor environment. Exposure assessments of various phthalate pathways were conducted on children and adults. Organic films were collected for analysis from 110 residential dwellings in metropolitan areas over a two-month period. The exposure assessments were categorized into inhalation, oral, and dermal exposure pathways. Diethyl phthalate was highest in inhalation exposure, dibutyl phthalate represented the highest dermal exposure, and bis(2-ethylhexyl) phthalate was identified as the highest contributor to oral exposure. For children, the primary exposure pathways included dermal absorption of DBP, DEP, diisobutyl phthalate (DiBP), butylbenzyl phthalate (BBP), and di-n-hexyl phthalate (DNHP); dust ingestion of DEHP and di-n-octyl phthalate (DNOP); and inhalation of dimethyl phthalate (DMP). The ECR and HQ for inhalation, dermal, and ingestion did not exceed the threshold in children and adults at all pollutants, suggesting no potential health impact. In contrast, the primary routes of exposure for adults were dermal absorption of DBP, DMP, DEP, DiBP, BBP, and DNHP, along with dust ingestion of DEHP and DNOP. The findings of this study provide valuable baseline data for future research in health risk and SVOC exposure assessments utilizing indoor organic films.

Tuberculosis (TB) and coronavirus disease 2019 (COVID-19), caused by Mycobacterium tuberculosis (MTB) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), respectively, are serious public health issues. N95 respirators are commonly used to protect people from infections in high-risk environments. Consequently, we used Mycobacterium smegmatis and bacteriophage MS2 as MTB and SARS-CoV-2 surrogates to evaluate the ability of a quaternary ammonium agent (QAA) coating on the surface of new N95 respirators to reduce the microbial burden upon aerosol exposure. Regarding the burden (10⁵ CFU (or PFU)/m³) of M. smegmatis and MS2 phage that settled onto the respirator surface, the QAA yielded average reduction efficiencies () of 92.4% and 99.8%, respectively. In addition, the antimicrobial activity of the coated respirator was maintained for one week. For bioaerosols that contacted the respirator (10⁵ CFU (or PFU)/m³), the of the QAA was 90.7% for M. smegmatis and 94.4% for MS2 phage on the outermost layer of the respirator. Moreover, filtration efficiencies between a QAA-coated respirator and an untreated respirator were not significantly altered (). These results demonstrate that this QAA product has a durable antimicrobial activity and could reduce the MTB and SARS-CoV-2 concentrations on the N95 respirator surface. However, it is recommended that such a coating respirator not be worn for more than 4 hours based on hemolysis assay results.

The risk of airborne disease transmission in hospital rooms during aerosol-generating medical procedures is known to be influenced by the size of the room, air ventilation rate, input-to-output flow ratio, vent surface area, and vent location. However, quantitative recommendations for each ventilation design parameter are scarce. Moreover, room layout and occupant activity parameters, such as furniture locations and healthcare worker movement, are often omitted from studies on airborne disease transmission in hospital settings. As a result, the development of policies and technologies aimed at mitigating airborne disease transmission in hospitals has been limited. To address this shortfall, this study is aimed at first characterizing existing ventilation, room layout, and occupancy parameters in hospital rooms where aerosol generation medical procedures (AGMPs) occur and then testing the hypotheses that ventilation, room layout, and occupancy parameters vary significantly between hospital rooms and, in some cases, with time. Information on AGMPs was collected via a survey circulated to healthcare workers within British Columbia’s Interior Health Authority (IHA), while hospital room and ventilation system information was collected by reviewing drawing packages of 37 IHA hospital rooms. The survey results indicate that AGMPs commonly occur in trauma, ICU, or general ward rooms with positive or negative pressure ventilation systems. Statistical tests, with room type (trauma, ICU, or general), room pressure (positive or negative), and/or time as independent variables, show that variables relating to ventilation (number of supply vents, supply and exhaust vent location, ventilation rate, and supply and exhaust area) and room layout (congestion score, room volume, light area, and number of lights) vary with room type but not with room pressure. Occupant activity variables (number of workers, number of moving workers, and speed score) also vary with room type, although to differing extent with room pressure and time. The survey and drawing review data presented in this study can help guide systematic comparisons of mitigative technologies as well as parametric investigations on how room layout, ventilation, and operational parameters influence airborne disease spread. This is a crucial first step in achieving quantitative and clinically relevant recommendations for mitigating airborne disease transmission in healthcare settings.