A mechanical engineer explains why cruise lines are so prone to spreading the coronavirus and why hospital ships are safer

US Navy hospital ship USNS Comfort

Outbreaks of COVID-19 on cruise lines like the Diamond Princess raise questions about how hospital ships will be any better at containing the novel coronavirus.
Two hospital ships are set to dock in New York and Los Angeles as US caseloads surge.
Mechanical engineer, Qinyang Chen, said that the ventilation systems onboard hospital ships make them equipped to contain the virus better than commercial cruise liners.
President Trump suggested that decommissioned cruise lines could be an additional asset if hospital ships aren’t enough, which may be a viable option if ventilation issues are addressed, said Chen.
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Luxury cruise ships like Carnival Corporation’s Diamond Princess have proven fertile ground for the spread of COVID-19. In contrast, two naval hospital ships —if operated with certain precautions — should safely halt transmission, says Qinyang Chen, a professor of mechanical engineering at Purdue University.

The 1,000-bed floating hospitals are set to dock in New York and Los Angeles in the coming weeks. Chen told Business Insider that the two ships’ air circulation systems are equipped to trap and eliminate virus particles, which didn’t happen on the Diamond Princess.

What went wrong on the Diamond Princess

Chen says researchers can’t prove how more than 700 passengers aboard the Diamond Princess came down with COVID-19. The virus could have spread through handshakes or coughs — even through tiny drops of toilet water spewed into the air when someone flushes. But after a quarantine confined most passengers to their rooms, how did the virus keep finding new victims? Chen suspects the air conditioning system.

Cruise ship cabins are vented with a mix of safe outdoor air and questionable indoor air. “You do get the fresh air from the sea,” says Chen. That ocean breeze should be free of the coronavirus. But “part of the air supplied to each room is returned back to the air conditioning system.” According to Chen, the danger lies in recirculation.

Each time the air circulates, it flies through a coarse filter that snags particles larger that 5,000 nanometers — that’s about the size of your red blood cells. But Chen says the coronavirus is likely dozens of times smaller, rendering the filter an open door rather than a blockade. “Those small particles that might contain the coronavirus are returned to the cabins,” says Chen. So the coronavirus could have spread between rooms, even if everyone followed the quarantine guidelines.

In the end, one in five (19.2 percent) Diamond Princess passengers tested positive for COVID-19. The high infection rate raises questions about the safety of using ships to expand hospital capacity as the US caseload surges.

Navy hospital ships to the rescue?

The US Navy is readying its two hospital ships for civilian service in April. At the request of local officials, the USNS Comfort will set sail for New York City, while the USNS Mercy will chart a course for Los Angeles.

The floating hospitals won’t admit COVID-19 patients — instead they’ll serve as intensive care units to treat …read more

Source:: Business Insider


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