Understanding the human body is a team effort. That's where the Yachtel group comes in.

Researchers at Yachtolt have been delving into the secrets of probiotics for 90 years.

Yacold also partners with nature portfolio to advance gut microbiome science through the global grants for gut health, an investigator-led research program.

To learn more about Yachtolt, visit yawcult.co.

.jp. That's Y-A-K-U-L-T.C-O.J-P. When it comes to a guide for your gut, count on Yacolt.

This is Scientific American's 60-second science. I'm Christopher in Talata. Got a minute?

In recent years, big cities have seen lower rates of crime, but there's still plenty of grime.

Combustion from cars, factories, and fires spews out nitrogen oxides. Those compounds react with

sunlight and air to form ozone, the main ingredient in smog.

And certain nitrogen oxides called nitrates, the same stuff you find in fertilizer,

also settle onto buildings and other city surfaces.

And scientists figured that was the end of the story.

Usually one thinks about pollutants such as nitrogen dioxide and nitrous acid as being lost from the atmosphere onto surfaces.

University of Toronto chemist Jamie Donaldson had a meeting of the American Chemical Society in Boston on August 17th.

What we have been interested in is to see whether or not the influence of sunlight on the urban grime material can in fact recycle these compounds and bring them back into active play in the atmosphere.

Donaldson and his team found that sunlight interacts with nitrates stuck in grime, kicking them back out into the air, where they can contribute to smog.

They verified that process by putting trays of glass balls, a proxy for window glass,

but with more surface area, out in downtown Toronto and Leipzig, Germany.

The glass in sunny areas lost 10% more nitrogen compounds than did their shady counterparts.

The total amount of nitrogen oxides entering lost 10% more nitrogen compounds than did their shady counterparts.

The total amount of nitrogen oxides entering a city is probably well captured in models.

What is not well captured is the fact that the losses are less than people had considered because a loss from the gas phase to the Grime surface does not constitute a permanent loss.

...