Each year, four million San Francisco Bay Area workers find themselves commuting some of the longest distances and times in the nation. While most are aware of some of the impact that driving has on the environment, there is a perhaps lesser known danger in our commutes that merits attention: tire microplastics, the primary contributor to microparticles littering the San Francisco Bay.

Plastic straws and bags have been banned to protect the environment, but that isn’t the biggest contributor to the seven trillion microplastic particles researchers found in the San Francisco Bay and surrounding areas. Shockingly, the main source of these microplastics were tidbits of tires that invaded through storm runoff and wind.

Microplastics are plastic particles less than 5mm in size (roughly the length of a pencil eraser) and found all across the San Francisco Bay. The presence of microplastics in the Bay is at higher levels than in other tested urban water bodies of North America, putting Californians at a higher health risk.

A study published in the International Journal of Environmental Research and Public Health noted that microplastics of this size easily find their way into humans through inhalation which can lead to respiratory disorders such as lung cancer. The findings also concluded that the ingestion of tire wear and tear microplastics through aquatic food intake “is to be expected.”

Tire microplastics are a common side effect of tire wear and tear, which can be accelerated by constantly stopping and starting in traffic, and magnified by long commutes.

Studies show the key to reducing tire microplastics is to keep your tires properly inflated. Proper tire inflation also provides other benefits to drivers in the long run, such as preventing rolling resistance when tires meet the rough surface of the road. This  requires more fuel consumption, thereby increasing carbon dioxide emissions.

Services like mobile fueling can assist during this time, both by fueling up vehicles (removing the commute to the gas station), as well as checking and inflating tires.

City governments in California need to push for state policy that improves transportation in the Bay and reduces traffic congestion. Until this occurs, or tires are made of a decomposing material, Californians need to take care to properly inflate their tires.