Upon exposure to air or sunlight it can turn brown and lose its efficacy.

But all those organisms had in fact died immediately upon exposure, or shortly thereafter.

Upon exposure to the public, Greenberg made a full confession.

Upon exposure, an individual must develop illness that is severe enough for them to seek medical attention.

The inside of the apple will turn brown upon exposure to the air.

Those with "wet" lubricants tend to dry upon exposure to air.

Class 3B can cause immediate eye damage upon exposure.

This material, upon exposure to air, changes from black to white and resembles washing soda.

Upon exposure, one should move to fresh air immediately.

Breath was frosting upon exposure to the night air and left a marked trail.