Tule Fog Blankets California’s Central Valley, Disrupting Travel

A dense layer of tule fog has covered large parts of California’s Central Valley for weeks, coinciding with reports of respiratory symptoms among some residents.

The fog has affected more than 20 counties across nearly 400 miles. 

The fog forms when the ground cools rapidly after sunset, causing moisture to condense near the surface and significantly reduce visibility.

According to Sky News, health experts stressed that fog itself does not cause illness, suggesting that other environmental or seasonal factors are likely behind the reported symptoms. 

The fog has, however, posed serious risks to transportation. The region has a history of major traffic accidents linked to dense fog, including a 108-vehicle crash in 2007 that killed two people, and another incident earlier this year that left two dead and nine injured.

Some residents also reported white residue on their cars, though experts confirmed that natural fog consists of pure water droplets and does not leave deposits. 

The World Health Organization has warned that trapped air pollution remains one of the leading causes of premature deaths worldwide.