On Dec. 18, 2024, researchers from the UC San Francisco released a study showing that tires and degrading garbage shed tiny pieces of plastic into the air, creating a form of air pollution that may be causing respiratory and other illnesses. A review of some 3,000 studies implicated these particles in a variety of serious health problems. These include male and female infertility, colon cancer and poor lung function.

Microplastics are less than 5 millimeters – smaller than a grain of rice – and they are ubiquitous in the environment. Each year, companies around the world produce nearly 460 million metric tons of plastic. That is projected to reach 1.1 billion by 2050. The paper was the first systematic review of microplastics using gold standard methods approved by the National Academy of Sciences.

The study expanded on a report the researchers produced in 2023 with the California State Policy Evidence Consortium (CalSPEC). The Consortium includes experts across the UC system and provides evidence for policymakers in the California State Legislature.