ATMOSPHERIC CHEMISTRY

Cities already deal with too much smog, but new research shows humidity makes it even worse. When air is moist, tiny chemical reactions happen faster and create more of the stuff that turns into harmful particles. Scientists tested this by simulating how city air reacts in controlled conditions. The

Nitrogen dioxide, or NO2, is a big player in the atmosphere's chemical game. It's a primary pollutant that sets off chain reactions leading to smog, acid rain, and tiny particles floating in the air. Scientists have been studying how NO2 behaves when it touches different surfaces, like dust, water d