Natural ventilation as a key Airborne Infection Control Measure for Tuberculosis Care Facilities.
Authors: Singh Raja 
Published: October 2019

Tuberculosis or TB has a large number of cases in India. India is fighting TB with the aim of eliminating it by 2025 (1) (2). TB, an airborne disease, has a risk of being hospital acquired (nosocomial) by the patients, visitors and the healthcare workers (HCWs). As a fact, till 2004, there were no studies on nosocomial Tuberculosis in India. (1) (3) The Guidelines on AIC or Airborne Infection Control (4) in Healthcare and other settings, released by the Directorate General of Health Services(Government of India) highlights the role of architects and engineers in Health Infrastructure Design for better infection control. The National Strategic Plan For Tuberculosis Elimination 2017–2025 (2) mentions AIC by highlighting the role of Natural Ventilation in limiting the infection spread in TB care facilities. Like TB, there are other diseases which also spread through the airborne route like Legionella pneomophila, Serratia marcescens and SARS (5). These are also linked to the ventilation of the hospital and have at multiple times revived the interest in the area of Indoor Air Quality for Healthcare facilities though there is an equal risk in Prisons, hostels, homeless facilities and long term care facilities. It was confirmed by the SARS epidemic in 2003 that the ‘mechanisms of respiratory disease transmission are still poorly understood.’ (6) and, there is a ‘lack of scientific evidence underpinning minimum ventilation rate guidelines (5).’ The Indian government literature too, mentioned above doesn’t have quantitative ventilation guidelines. The AIC guidelines have three types of measures namely, Administrative, Personal Protective and engineering/environmental control (7). The cost of many suggested engineering measures are high, and the more affordable measures include improving natural ventilation by opening the windows (8). Ventilation systems not only have an issue with air changes but also are likely to be compromised by poor design, faulty construction or inadequate maintenance which has led to the occurrences of TB (and related diseases) outbreaks. (8)There have been studies in Thailand and Peru which state that naturally ventilated rooms had a higher air change rate. (8) (9)The study in Peru also went on to state that the highest risk of infection occurred in mechanically ventilated rooms with sealed windows, despite being ventilated at recommended rates. As the thrust towards energy-efficient buildings increases, there is a higher chance of making compact spaces which are airtight and use HVAC. (10)Such buildings have been studied to report an increasing trend of airborne infections. There is a need to consolidate the literature available and perform further studies to provide functional and quantitative guidelines to architects for better AIC. (1) Architects, and other infrastructure professionals, need to play a proactive role driven by performance-based research and evidence-based design to design better TB care facilities with the aim of reducing the airborne infection. For this, there needs to be a special focus on the use of natural ventilation and its unexplored potential for infection control.