EAST PROVIDENCE, R.I. (WPRI) — Experts at NASA say a hole in the ozone layer appears to be decreasing in size.

The ozone layer is a portion of the stratosphere that protects Earth from the sun’s ultraviolet rays.

According to NASA, the hole over Antarctica had an average area of 8.91 million square miles in 2022, which is slightly smaller than the previous year’s measurement of 8.99 million square miles.

“Over time, steady progress is being made and the hole is getting smaller,” Paul Newman, chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center, told NOAA. “We see some wavering as weather changes and other factors make the numbers wiggle slightly from day to day and week to week, but overall, we see it decreasing through the last two decades.”

According to NASA and NOAA, the hole occurs when the protective ozone layer begins to thin every September. A combination of chlorine and bromine from human-produced compounds are released. The reaction from these chemicals then deplete the ozone layer as the sun rises in late winter in the Southern Hemisphere.

The strongest depletion occurs over Antarctica, according to NOAA.