As the case count of coronavirus infections continues to rise in China, the number of reported infections among children is remarkably low.
"We're seeing [about] 75,000 total cases at this point, but the literature is only reporting about 100 or so pediatric cases," says Terri Lynn Stillwell, a pediatric infectious disease expert at Mott Children's Hospital at the University of Michigan.
It's possible that many more kids are infected but don't get sick enough to seek medical treatment. It's also possible that some infected children may develop no symptoms at all.
One of the substances with the lowest odor detection threshold is vanillin, the main component of vanilla extract. Estimates vary, but its odor detection threshold is probably around 0.1 or 0.2 micrograms per cubic meter, significantly lower than ethyl or methyl mercaptan. That means that one or two oil tankers full of vanillin could conceivably be used as an air freshener powerful enough to give the entire Earth a slight scent of vanilla.