Then for the next hour, a high tech machine collects air samples, to gauge something called"air change," or how many times the air in that room is completely changed each hour through the ventilation and air conditioning systems.
"It is now widely recognized that clean indoor air is the key to getting workers safely back to workplaces, students safely back to schools," said epidemiologist Dr. David Michaels, at a White House Summit on Indoor Air Quality held earlier this month.
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