Apple and Facebook have been stockpiling millions of face masks for months — just not for the coronavirus, officially known as COVID-19. referred to as coronavirus.

The tech giants announced this week that they were donating a combined 9.7 million masks to help fight the deadly pandemic, medical equipment originally stored following a different disaster: last years’s California wildfires.

The companies were following a new regulation from the state’s Occupational Safety and Health Standards Board, CNBC reports. 

The new rule requires companies to provide respiratory equipment, like N95 masks, for workers when air quality dipped, according to the report.

The board added that substitutes like scarves or clothing tied around someone’s nose and mouth, as well as surgical masks, would not be sufficient to protect people from smoke inhalation as the wildfires intensified.

The regulation states that an “N95 filtering facepiece respirator … is the minimum level of protection for wildfire smoke.”

Particulates in the air are the problem when it comes to using masks without the respirator facepiece.

The Centers for Disease Control and Prevetion (CDC) issued the following statement: “In settings where face masks are not available, [health care personnel] might use homemade masks [e.g., bandanna, scarf] for care of patients with COVID-19 as a last resort. However, homemade masks are not considered [personal protective equipment] since their capability to protect [health care personnel] is unknown. Caution should be exercised when considering this option. Homemade masks should ideally be used in combination with a face shield that covers the entire front [that extends to the chin or below] and sides of the face.”

Our teams at Apple have been working to help source supplies for healthcare providers fighting COVID-19. We’re donating millions of masks for health professionals in the US and Europe. To every one of the heroes on the front lines, we thank you.

— Tim Cook (@tim_cook) March 21, 2020

Though nearly 10 million might sound like a lot of masks, federal officials have estimated the real need over the course of the next year is up to 3.5 billion masks given the quick spread of the disease. 

Thousands of medical workers across the country have made public pleas to friends and family on social media to donate their N95 masks or sew masks which could serve as makeshift replacements. Infection rates among hospital personnel is incredibly high compared to the general population in the hardest-hit places. 

In Italy, people are using 3D printers to make N95 mask and ventilator substitutes. Car manufacturer Ford also announced it will partner with 3M and GE Healthcare to begin producing not just N95 masks but also ventilators, which are also in short supply, particularly in New York City.