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The Daily Cardinal Est. 1892
Friday, April 19, 2024

Ask Mr. Scientist: From ozone to compostable chip bags


Dear Mr. Scientist,

Why is ozone good when it’s up in the atmosphere, but bad when it’s down at ground level?

—Sasha R.

When ozone (O3) is in the stratosphere, it does a good job of absorbing ultraviolet light from the Sun. Without this thin layer of ozone, that ultraviolet light would be very hazardous to our health and could cause things like skin cancer and cataracts. When it’s near the ground, however, ozone is less helpful. Instead, it can cause serious lung damage and other health problems in humans. It interferes with the ability to make and store food in plants and can destroy materials like latex and plastics. Ozone at ground level is also a key ingredient of smog. Emissions from car exhaust are a major contributor to ground level ozone, so riding your bike or walk when possible to help reduce the amount of ozone pollution.

Dear Mr. Scientist,

How do things like compostable chip bags work? I thought plastic wasn’t biodegradable.

—Chris W.

There are actually a couple of ways to create plastics that will break down when buried. First, there are plastics that are made from natural materials like corn starch. When the plastic material is buried, the corn starch molecules absorb water and break apart, making it easier for bacteria to digest the plastic. Another method that involves corn is using the sugar in it to create a type of plastic called polylactide acid. Unlike traditional plastics like polyethylene and polypropylene, polylactide acid is biodegradable. A third method uses normal petrochemical plastics, but contains additives that cause the plastic to decay faster in the presence of light and oxygen. There are more ways to create biodegrable plastics as well, but every method has its downfall. The best option is to keep plastic products out of landfills and recycle them.

Mr. Scientist is Michael Leitch. If you have a burning science question you want him to answer, e-mail it to

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