Pollution sparks free radicals. These molecules are created as normal byproducts of cell metabolism or by exposure to external sources like X-rays, air pollution, cigarette smoking, and pesticides. 

Free radicals have an uneven number of electrons, which poses a problem—because electrons “like” to be in pairs. This means free radicals will steal electrons from healthy molecules to stabilize themselves. Then that molecule turns into a free radical, and the chain reaction continues. 

When your skin gets exposed to these free radicals, it enters a state called oxidative stress, and a prolonged state of oxidative stress speeds up the skin aging process1. 

Specifically, it contributes to the loss of collagen and elastin fibers, resulting in fine lines, sagging, and textural changes. It can also trigger dark spots for some. 

But it’s not just about these “signs of aging”—oxidative stress affects skin’s basic functions: Oxidative stress is also involved in reduced barrier function, increased sensitivity, and decreased moisture. 

Hence, why your skin may be more sensitive and dry during times of increased air pollution.