Wind-driven roof turbines' effectiveness in enhancing household ventilation: a potential tool to reduce tuberculosis infection

Background: South Africa's overburdened healthcare systems have led to criticism of its unsustainable tuberculosis management interventions. In 2011, the National Department of Health implemented an outpatient, decentralised care model, but this increased costs and jeopardised the long-term viability of prevention measures. Home confinement is now recognised as a viable intervention option, when combined with safety precautions such as ventilation and medical support. However, little is known about the risk of infection in this context. Objectives: To assess the effectiveness of wind-driven roof turbines in enhancing ventilation and their potential to lower the risk of Mycobacterium tuberculosis infection in a residential setting. Methods: Eight houses were selected and divided equally into intervention (wind turbines installed) and control groups, using a pairwise comparison method. The CO2 decay method was used as a proxy to determine ventilation in the houses. The wind-driven roof turbines' potential to lower the risk of Mycobacterium tuberculosis infection was stochastically evaluated using the Wells-Riley mathematical model. Results: During two seasons, installation of a roof turbine resulted in twofold ventilation rates compared to the control houses. Consequently, the WellsRiley model predicted a twofold reduction in the probability of infection in the intervention compared to the control households. Conclusion: Low-cost, low-maintenance wind-driven roof turbines are effective in increasing ventilation in houses, and should be considered as an additional layer of protection against Mycobacterium tuberculosis and other infections in residential settings.

Contaminação do ar em salas cirúrgicas durante cirurgias de artroplastias total de quadril e joelho, hemiartroplastias e osteossínteses no centro cirúrgico de um hospital Brasileiro / Air contamination levels in operating rooms during surgery of total hip and total knee arthroplasty, hemiarthroplasty and osteosynthesis in the surgical center of a Brazilian hospital

INTRODUÇÃO: Avaliou-se o nível da contaminação do ar em cirurgias ortopédicas. MÉTODOS: O ar das salas cirúrgicas foi analisado microbiologicamente através da exposição de placas próximas à mesa cirúrgica por uma hora. RESULTADOS: Foram evidenciados valores acima do recomendado (369 UFC/m³) nas salas convencionais, assim como naquelas com ar ultralimpo. A contaminação foi predominantemente por Staphylococcus sp (86,9 por cento). verificou-se um número alto de pessoas presentes no interior das salas cirúrgicas, assim como de abertura da porta. CONCLUSÕES: Os níveis de contaminação se apresentaram acima dos valores aceitos por agências reguladoras, representando risco para os pacientes.

INTRODUCTION: The air contamination levels during orthopedic surgeries were evaluated. METHODS: The air of operating rooms (ORs) was examined through exposure to microbiological plates placed near the surgical table for an hour. RESULTS: values above that recommended (369 CFU/m³) for conventional ORs and ORs with ultraclean air were determined. Contamination was predominantly by Staphylococcus sp (86.9 percent). In all surgeries a high number of people were present inside the ORs and the doors were opened frequently. CONCLUSIONS: The contamination levels are above the values accepted by regulatory agencies, representing risk for patients.

Risk of Transmission of Airborne Infection during Train Commute Based on Mathematical Model

Objective: In metropolitan areas in Japan, train commute is very popular that trains are over-crowded with passengers during rush hour. The purpose of this study is to quantify public health risk related to the inhalation of airborne infectious agents in public vehicles during transportation based on a mathematical model. Methods: The reproduction number for the influenza infection in a train (RA) was estimated using a model based on the Wells-Riley model. To estimate the influence of environmental parameters, the duration of exposure and the number of passengers were varied. If an infected person will not use a mask and all susceptible people will wear a mask, a reduction in the risk of transmission could be expected. Results: The estimated probability distribution of RA had a median of 2.22, and the distribution was fitted to a log-normal distribution with a geometric mean of 2.22 and a geometric standard deviation of 1.53, under the condition that there are 150 passengers, and that 13 ventilation cycles per hour, as required by law, are made. If the exposure time is less than 30 min, the risk may be low. The exposure time can increase the risk linearly. The number of passengers also increases the risk. However, RA is fairly insensitive to the number of passengers. Surgical masks are somewhat effective, whereas High-Efficiency Particulate Air (HEPA) masks are quite effective. Doubling the rate of ventilation reduces RA to almost 1. Conclusions: Because it is not feasible for all passengers to wear a HEPA mask, and improvement in the ventilation seems to be an effective and feasible means of preventing influenza infection in public trains.

Risk of transmission of airborne infection during train commute based on mathematical model

<p><b>OBJECTIVE</b>In metropolitan areas in Japan, train commute is very popular that trains are over-crowded with passengers during rush hour. The purpose of this study is to quantify public health risk related to the inhalation of airborne infectious agents in public vehicles during transportation based on a mathematical model.</p><p><b>METHODS</b>The reproduction number for the influenza infection in a train (R(A)) was estimated using a model based on the Wells-Riley model. To estimate the influence of environmental parameters, the duration of exposure and the number of passengers were varied. If an infected person will not use a mask and all susceptible people will wear a mask, a reduction in the risk of transmission could be expected.</p><p><b>RESULTS</b>The estimated probability distribution of R(A) had a median of 2.22, and the distribution was fitted to a log-normal distribution with a geometric mean of 2.22 and a geometric standard deviation of 1.53, under the condition that there are 150 passengers, and that 13 ventilation cycles per hour, as required by law, are made. If the exposure time is less than 30 min, the risk may be low. The exposure time can increase the risk linearly. The number of passengers also increases the risk. However, R(A) is fairly insensitive to the number of passengers. Surgical masks are somewhat effective, whereas High-Efficiency Particulate Air (HEPA) masks are quite effective. Doubling the rate of ventilation reduces R(A) to almost 1.</p><p><b>CONCLUSIONS</b>Because it is not feasible for all passengers to wear a HEPA mask, and improvement in the ventilation seems to be an effective and feasible means of preventing influenza infection in public trains.</p>