Heating, ventilation, and air-conditioning (HVAC) systems are used to provide comfortable environmental conditions and clean air in indoor settings such as buildings and vehicles. Poor ventilation is associated with increased respiratory infection transmission in enclosed indoor spaces. Numerous COVID-19 transmission events, including those from presymptomatic cases, have been associated with closed spaces. The role of ventilation in avoiding the transmission of COVID-19 is not well-defined. A growing number of reports suspect that COVID-19 is mainly transmitted through large respiratory droplets, that is the position of aerosols in outbreaks. So Ventilation is blamed for COVID-19 spread. Aerosols consist of tiny droplets and nuclei of droplets that stay longer in the air than large droplets. 

While poor ventilation is one of the causes of rapid transmission, this problem cannot be easily tackled as the hospitals and medical wards all around the world are facing a shortage of ventilators. 

Investigators at Melbourne hospitals have found it is normal for air to be fed into busy corridors in rooms with ill patients, with inadequate ventilation and airflow problems. Since nurses and other health workers started to catch the virus in their hundreds, several teams of engineers spent months studying the airflow in hospital wards and treatment rooms. Tests that used smoke to measure where air moves detected air from the rooms of patients circulating at the stations of nurses.

Ventilators are not extraordinarily complex devices in terms of their core purpose. Basically, they are sophisticated pumps that regulate the flow of oxygen and air from the lungs of the patient, supporting them while they are unable to do their job. Why are they so hard to build, then? Because it is not their function that is challenging. It’s that they have to work in a high-stakes setting in an incredibly secure way. If they fail, the patient is very likely to die. But while high-income nations might have the ability in weeks to scale up an industrial initiative, most countries do not. And even high-income countries may find themselves in a position where they need additional ventilators, too: there are reports that prices are skyrocketing as the demand rises globally. This may seem funny but if we hit the stage where, since there are not enough ventilators, hundreds of thousands or millions of people are dying, then the DIY ones are the backup.