A novel personal ventilation strategy to circumvent aerosol transmission

In the pandemic of COVID-19, a rigorous lockdown or social distancing will mitigate transmission, but some alternative strategy is needed especially for mass-gathering events. Given that the main path of transmission is through droplets or aerosols, a swift removal of them immediately after exhalation, which may attain “personal air zoning”, would be more effective and feasible than whole room ventilations. In the present study, an artificial fog was employed as a model aerosol to be exhaled and readily visualized on movies and quantified on dust indicators. The temporal and spatial distribution of this model microdroplet amounts corresponded reasonably well with previously published data, where talking air flow was quantified as a negative staining, in that it predominates below the mouth height rather than horizontal, and that it travels forward over 1.5 m in 30 sec. Under this model condition, nearly 99% of exhaled microdroplets could be efficiently blown up beyond the bystanders’ head heights, when a minimal air flow (2.5 m/s) was applied, using a typical personal cooling fan just below the chin. This swift upward removal of microdroplets would prevent bystanders’ immediate inhalation and provide sufficient probation periods for safe exhaustion from indoor spaces.

Formation of local temperature regime in the room: personal ventilation system

The peculiarities of a person’s metabolism are related to the state of health, age, and other personality traits, which determines the need for a personal value of the ambient air temperature. Individualization of work and recreation of people requires the creation of local temperature zones in the room with the air temperature necessary for a particular person, which will increase labor productivity, reduce morbidity, since the stress of the human thermoregulation system will be minimal. In addition, the personalization of the microclimate in the workplace in the room with the creation of local temperature zones will allow you not to waste heat and electricity where it is not needed, creating additional opportunities for energy saving potential in the premises of the building. The article deals with the personalization of the operation of the ventilation system in the room with the formation of vertical conical air jets coming from the ceiling of the room to the workplace, considering the requirements of regulatory documents for the air velocity in the working area of the room.

Socio-Economic and Environmental Risk Factors of Tuberculosis in Wonosobo, Central Java, Indonesia

This study discusses the dominant socio-economic and environmental risk factors for TB disease. The design of this study was a case-control study with 70 case samples and control with a contribution of n = 1. Variables from this study contacted personal, ventilation of the house, humidity, the temperature of the house, density of the house, kitchen, and family earnings. Multivariate data analysis uses multiple logistic regressions. The study notes that from 140 samples, 47% have basic education, and 30% are farmers. People who had a past of contact with TB cases were ten times more likely to contract TB than those who had no contacted (OR = 10.00; p <0.001). Personalities who live in poorly ventilated homes who have a risk of contracting TB are 2.2 times greater than those who live in homes with standard ventilation (OR = 2.20; p <0.018). The moisture increases the risk of TB by four times the low moisture (OR = 4.00; p = 0.001). Living in a house with a higher temperature of TB is 3.8 times higher than a lower temperature (OR = 3.80; p = 0.009). Living in a high population density of the house improves TB five times more than living in a lesser home (OR = 5.00; p <0.001). Kitchen gas enhances the risk of TB 2.5 times greater than gasless (OR = 2.50; p = 0.007). Low family earnings raise the risk of TB three times greater than high family earnings (OR = 3.00; p = 0.002). A past of contact, poorly ventilated homes, high humidity, hothouse temperature, population density, kitchen gas, and low family earnings, are risk factors for TB in Wonosobo, Central Java.

Air Terminal Devices Developed for Personal Ventilation Systems

Using the personal ventilation systems may improve the thermal comfort sensation. At the University of Debrecen, a personal ventilation system was developed named ALTAIR. This paper presents the results of mean air velocity, turbulence grade, and draught measurements related to newly developed air terminal devices which are connected to the ALTAIR personal ventilation system. In order to define the measurement points it was essential to test the new air terminal devices (ATDs) in front of a black wall and smoke puffs. A series of measurements were carried out with isothermal air flow, mean air velocity, turbulence grade, and draught around the occupant head region in order to improve the thermal comfort sensation. Five different ATDs were analyzed.

Carbon dioxide as the main hazard in the design of personal ventilation systems

Mental work, used everywhere at present, is quite diverse and is characterized by various degrees of responsibility, monotony, attention, and the level of emotional stress. To provide comfortable living conditions for a person in a permanent workplace, it is also necessary to organize air conditioning systems. The most promising for this activity are personal ventilation systems, which provide a high-quality air environment in the area of human breathing while reducing capital and operating costs in comparison with traditional (mixing, displacement ventilation). However, when designing personal ventilation systems, one should not focus on the “average reference man”, but take into account the individual characteristics of the employee (age, gender, etc.) performing a specific type of mental activity. In order to clarify the actual value of carbon dioxide (with a certain degree of error) emitted by a person in a certain mental work, we perform a series of experiments. The authors conducted a significant amount of full-scale experimental investigations, the result of which is the confirmation of nature and dynamics of carbon dioxide`s changes in the room in the absence (inactivity) of ventilation systems (linear dependence), as well as the refinement of the amount of carbon dioxide emitted in a particular type of mental activity. It should be noted that this work is the beginning of large-scale scientific research designed to collect and systematize data on emissions of harmful substances from people engaged in various types of mental activity.