It may seem like a small switch, but it's having a big impact on some asthma sufferers.
20 million Americans live with asthma, and depend on their inhalers when breathing becomes difficult.
8-year-old Caileen Perez needs hers during exercise.
Her mother, Hilary says, "Sometimes when she's running the track at school, it can create some wheezing, or exercise-induced asthma is what they call it."
Now , Caileen's asthma inhaler has officially "gone green."
It no longer uses CFC's - chlorofluorocarbons - as a propellant to get the medicine into her body.
In fact, by the end of this year, inhalers with CFC's will no longer be sold in the U-S.
It's part of the 1987 Montreal Protocol, designed to cut substances that would deplete the earth's ozone layer.
New inhalers use propellants called HFA's.
Experts say patients won't experience that cold blast with the newer inhalers, but will still get the same, effective medicine.
Dr. Allen Lieberman, of the Allergy & Asthma Center of Austin, Texas, says, "When they did the studies, they did show that people attain the same amount of broncho-dilation that lungs opened up after using the medicine. So head to head, it works just as well as the others."
But asthma patients - who are already victims of air pollution - aren't all convinced.
The new inhalers contain a small amount of ethanol, which can irritate the lungs.
Some users say they aren't as effective at stopping asthma attacks.
Others complain of shortages, as companies stop making the old type, and gear up for the new ones.
William Graham, who used an inhaler a lot during a recent bout of pneumonia, noticed another big difference.
He says, "The taste is a little different."
But the biggest impact is price!
In some cases, the cost has tripled - a hardship for the many asthma sufferers on limited incomes, or with no prescription drug plan.
Angry patients note that no one is putting restrictions on gas-guzzling cars, backyard grills, or coal-fired industrial plants.
William says his co-pay has really jumped. He says, "It's a higher amount. I think I pay $22 instead of $3."
Some inhalers also have a shorter shelf-life - one lasts 2 months after it is opened, compared to 15 months for the older version.
Doctors say that by controlling asthma with preventive medications, most patients should only need one rescue inhaler per year.
Patients who are having a hard time affording inhalers can call the Partnership for Prescription Assistance, toll-free at 1-888-4-PPA-NOW - 1-888-477-2669.