From flames to haze, wildfire smoke transforms as it travels, and it can harm your health in different ways

Wildfire smoke plumes undergo dramatic changes as they travel across the country, transforming from bright red plumes to hazy, invisible clouds. The transformation alters not only the smoke's appearance but also its composition, posing varying health risks as it reaches different regions. To understand how smoke evolves, researchers must consider the smoke's origin and the factors that influence its evolution.

Wildfire emissions vary depending on the intensity of the fire. High-temperature wildfires emit nitrogen oxides, which create secondary pollutants and reactive carbon compounds that pose long-term cancer risks. Smoldering wildfires release different compounds but also contain toxic aromatic oxygenates and ammonia, which irritate the respiratory system.

Wildfire smoke's journey is governed by wind speed, atmospheric temperature, and sunlight. Smoke moves horizontally due to wind (advection) and vertically when it's lifted from the ground by powerful upward winds. High-altitude winds transport smoke thousands of miles, while sunlight acts as a chemical engine, breaking apart molecules and creating reactive species that form ground-level ozone, a key component of smog.

When smoke reaches a city, it can mix with urban pollution, creating additional local ozone and exacerbating health risks. The distinctive smoky aroma of fresh smoke disappears within hours due to sunlight and chemical reactions. The final, hazy, milky white smoke that drifts across the country is chemically distinct from the original emissions but remains a serious health hazard.