COVID-19 and Ventilation: Historic and Modern Solutions to Deploy

As fears rise about post-Labor Day effects and the reopenings of schools from kindergarten through the university level, and the number of U.S. COVID-19 cases surges to more than 6 million, it is prudent to examine additional prevention methods through ventilation.

I have seen the effectiveness of HEPA, or high efficiency particulate air filter systems, firsthand. I made rounds recently in an Open COVID-19 ICU at New York University-Langone. As I treated patients, the roaring jet engine sounds added to the sense of foreboding, but ultimately contributed to the safety of each doctor aiding very ill COVID patients.

The ventilation kept the viral burden circulating around us diluted in large currents of moving air. Despite serving almost 50 days rotating in the ICU, I did not contract COVID-19.

Many area doctors reported the same results. Only 12 percent of health care workers showed antibodies in May, despite very high exposure, while more than 20 percent of the general population sheltering at home demonstrated antibodies.

A manuscript from 239 signatories in the Journal of Clinical Infectious Disease lends greater import to the role of ventilation in COVID treatment, with undeniable evidence that the pandemic is transmitted in the air.

These hundreds of scientists agreed in a statement that COVID is spread by aerosol or droplet modes of transmission (from a cough, sneeze or close contact in medical procedures), and also by direct airborne transmission.

Reports confirm many other hospitals around the country have been using ventilator systems to reduce transmission rates. This observation — reluctantly acknowledged but yet to be endorsed by the World Health Organization — is critical information.

The Canadian government recently released public health guidelines for a mitigation of risks for COVID-19 cases, with a section on ventilation that suggested “move activities outdoors when possible; ensure that the ventilation system operates properly; increase air exchanges by adjusting the HVAC system and open windows when possible and if weather permits.”

Experts recognize that managing airborne transmission with simple engineering of negative pressure ventilation that includes HVAC systems that extract air and not recirculate it, and HEPA filters, could hasten a flattening of COVID resurgence.

The concept of clean air as a deterrent to infection has been integral to good medicine for centuries as well as the practices of quarantining and isolation.

The first hospitals in the early 8th century Islamic empire were in what is now Syria, which opened the first shelter for the sick in Damascus in 707 under the rule of Umayyad Calipha-Al Walid. The world’s first Islamic hospital was founded with Syrian Christians in a society of charitable organizations including ‘leper houses.”

These healing centers developed the blueprint for hospitals today, with separate areas for patients with similar clinical conditions or identities. Most often at the center of the hospital was an outdoor garden where recuperating patients could take in the air.

The role of fresh air and sunlight gained traction in the late 18th and early 19th centuries, leading to the creation of specific architecture with the purpose to aid recovery. With the onset of the Industrial Revolution in 1760, the urban poor, living and working in crowded unsanitary conditions often contracted tuberculosis, while the wealthy could retreat to European spa destinations to “take the air.”

Today, the overwhelming emphasis on controlling the spread of COVID-19 has been on masking, social distancing and quarantining, based on the delayed recognition that transmission of COVID was human to human. It is a delayed understanding that the coronavirus is airborne.

Certainly when HVAC systems are configured to recirculate air they can also promote the spread of infection, as was evident in the SARS pandemic 2002-2004 when recirculated air was shown to infect to others.

However, if correctly configured to drive the flow of air into the atmosphere at a constant net negative airflow, and also diluting the air inside the building with clean air from outdoors, these systems can be a critical tool of infection control. They can contribute to the mitigation of an airborne viral pandemic.

The conundrum is that most modern public buildings — including hospitals — are hermetically sealed. No one is able to open windows to alter temperature or humidity. Certainly, during the frigid winter months, it will be problematic without shelter from outside air, but in many areas of the country for many months of the year, this is desirable.

In homes with modern HVAC systems, the internal environment is so efficiently sealed that overnight ambient CO2 levels from exhaled carbon dioxide rise to as much as 900 ppm, an exposure sufficient to cause headaches and poor sleep quality. It can be resolved by sleeping with a bedroom window cracked open.

Private business have reportedly been upgrading their HVAC systems even as some in the public sector — public schools and universities — remain stymied with how to address the pandemic.

Combining modified HVAC systems with Germicidal UVC light can further combat airborne viral burden. In use since the early 19th century to sanitize and kill mold and yeast viruses, this approach can also improve and safeguard indoor air quality.

Using UVC light at 200 to 280 nanometers in public spaces at a higher rate than the standard germicidal UV lamps’ operation at 254 nanometers can sanitize an empty operating room or an empty hospital room. The caution is this does pose skin cancer and eye disease risks to people exposed to this light.

Recent investigators at Columbia University Irving Medical Center have found “FAR-UVC light” at 222 nanometers can be used instead, without adding health risks. This can eliminate 99.9 percent of airborne viruses in a 25-minute exposure.

The need is for reversing ventilation to convert these buildings to exhaust more air than they draw in, re-engineering to have windows that can be opened to the fresh air, and possibly removing doors in doorways. These efforts may prove momentous in not only stemming the continued resurgence of COVID, but in allowing for safe re-openings of businesses and public spaces.

Certainly, common sense needs to play a role in avoiding large social gatherings, particularly after Labor Day weekend.

At University of Notre Dame for example, classes had to move online after the university “reported 80 new confirmed coronavirus infections,” indicating “a 19.1% positivity rate, nearly four times the rate that the World Health Organization recommends for states to reopen,” according to CBS News.  Similarly, a cluster of new COVID-19 cases was linked to a party at the University of Tennessee.

A focus on avoiding large crowds, wearing face masks, practicing hand hygiene and social distancing is important, but neglects the contributions of the built environment and the ability to innovate and engineer the air we breathe.

Combining all approaches in concert may offer the most effective solutions.

Qanta A. Ahmed is a senior fellow, Independent Women’s Voices, and pulmonologist, New York University-Langone.

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