Forty years ago while operating on a trauma victim who fell asleep at the wheel, I became more tired than usual despite the adrenaline rush to save a life. After completing surgery and removing the mask, I was wide awake again.

At that time, physiologically, it was explained to me that exhaling into the mask made it more likely to inhale my own expelled carbon dioxide. Most of the time this is not a problem, but since surgery took six hours, it was thought that using a mask exposed me to higher CO2 concentrations.

With the COVID-19 crisis, it is now recommended to wear a mask outside most of the time.

Be aware, though: Usage of a mask might cause some to have increased CO2, or possibly even decreased oxygen. If you experience sleepiness, tiredness or mental confusion, find a safe place to remove it for a while.

Using masks is critical for all of us because the benefit far outweighs the risk.

Should you be wearing one, please be especially careful when driving so you don’t fall asleep at the wheel.

Gene Uzawa Dorio, M.D., is a geriatric house-call physician who serves as president of the Los Angeles County Commission for Older Adults and Assemblyman to the California Senior Legislature. He has practiced in the Santa Clarita Valley for 32 years.