Worried about the virus? It may be seeping silently around us in ways we haven’t thought of.
Through air ducts, for example.
Indoor air quality experts warned state legislators in hearings this summer that building heating and ventilation systems play a larger role than suspected in the airborne spread of the COVID-19 virus. Scientists now recognize that indoor airborne spread is a more serious hazard than earlier thought.
Evidence now shows the virus, in the form of small droplets, can remain airborne in an enclosed space for several hours, members of the House State Affairs and Health and Social Services committees were told by experts in July. It has been shown that other viruses, like the SARS COV-2 virus, are spread through ventilation systems and the same can be true of COVID-19.
Despite the risk, which is confirmed by the U.S. Center for Disease Control, the state administration appears to be taking no so far steps to reduce the hazard in public buildings, said state Rep. Zack Fields, D-Anch., who chairs the House State Affairs Committee.
The exception to this appears to be at the state’s Pioneers Homes where ventilation systems have been upgraded, said Fields, in an interview Friday. Changes in settings for ventilation systems are easily done as well as upgrades of air filters, so it’s a low-cost way of improving protection against transmission of the virus.
The expert that appeared this summer included Shelly Miller, mechanical engineering professor in the University of Colorado Boulder’s Environmental Engineering Program; Julia Luongo, air quality consultant with Ramboll, and Mark Catlin, industrial hygienist with MDC Consulting and Training. They appeared before legislators in the two committee meetings.
Miller said COVID-19 is spread through the touching of contaminated surfaces but more through so airborne transmission, which is why the wearing of face masks and physical distancing when indoors is so important.
National air quality experts are in agreement. “The virus travels through respiratory droplets or small particles produced when an infected person coughs, sneezes, sings, talks, or breathes,” said Joseph G. Allen, associate professor, director of the Healthy Buildings program at Harvard and Linsey C. Marr the Charles P. Lunsford professor of civil and environmental engineering at Virginia Tech, in a Sept. 22 Op-Ed in the Washington Post.
“These particles can be inhaled into the nose, mouth, airways, and lungs and cause infection. Scientists now think this is the main way the virus spreads,” Allen and Marr wrote. “Our whole field has been shouting from the rooftops that airborne transmission was happening and that ventilation and filtration were crucial to limiting the spread of the disease,” the two wrote in the Op-Ed.
In Alaska, a focus on building energy efficiency in buildings has exacerbated the problem. Energy efficiency improvements in recent decades have focused on insulation and recirculation of indoor air, Catlin and Miller said.
Most buildings today are designed for 80 percent recirculated indoor air and 20 percent outdoor air, Miller said, but the best safeguard is circulation of 100 percent outdoor air, although this would raise heating costs. Recirculated indoor air can also be treated with filters to some extent and ultraviolet radiation shows promise as a way to kill viruses, but these steps are expensive, too.
Ultraviolet systems must be installed by trained technicians or engineers, said Catlin, a 40-year industrial hygienist who has worked in Alaska on indoor air quality
Catlin said initiatives on energy conservation in the 1980s and 1990s aimed at reducing the amount of outdoor air circulation particularly in cold weather, and that idea needs to be reexamined.
“There is guidance available (for adjusting systems in buildings) but the first step is to monitor a system and update it if possible and to verify that the systems are working properly. We recommend increasing the amount of outside air in the building if that is possible and to use higher-grade filters where filtering is done,” Catlin said.
COVID-19 presents an unusual challenge but Alaskans have a of experience in improving heating and ventilation of indoor spaces dating from those initiatives, Catlin told lawmakers. It is an area where state occupational and health safety as well as the University of Alaska Anchorage and University of Alaska Fairbanks engineering departments could work together on solutions.
Fields and other legislators in the hearings expressed concern that this isn’t happening and that there are no standards or protocols for heating and air systems in public buildings. Catlin said the state could easily draw on experience in other states. California, for example, has recognized that cornonaviruses are capable of indoor aerosol transmission and has set enforceable regulations, he said.
Alaska should do the same with an enforceable minimum standard for indoor air circulation. In lieu of a regulatory standard, renovation and monitoring in public buildings could provide a model for the private sector, Catlin said.
Rep. Zack Fields, House State Affairs chair, said he knows of no state building, except for Pioneer’s Homes, where ventilation systems are being renovated as a virus protective measure.
The science in the airborne transmission ia straightforward: “When you talk or sing — or even just breathe — you emit a range of particles of different sizes,” Allen and Marr wrote in the Op-Ed.
“There might be one or two particles that are large enough to see and that fall to the ground within six feet, but there are also thousands of particles that are smaller than five microns (or five millionths of a meter).” aThe two wrote.
“Such particles stay aloft for minutes to hours and can travel all the way across a room on natural air currents. They don’t stop at six feet. They will stay in the air in the room until they are pushed outdoors by ventilation, trapped on a filter if you have one, or deposited in your lungs.
“More importantly, among particles that stay in the air long enough to be inhaled, those smaller than five microns actually carry more virus than the larger ones, counterintuitively,” Allen and Marr wrote.
Research has also found that air samples collected 16 feet away from a patient contained infectious coronavirus. Case studies of “superspreading events” of the disease — from restaurants, buses, camps and choir practices — show common threads of time indoors, crowded conditions, poor ventilation and no masks, Allen and Marr wrote.