Higher Geography – Atmosphere Practice Test 2026 - Free Practice Questions and Study Guide

The main idea here is which substances in the air directly affect air quality and what they do once in the atmosphere. Sulfur dioxide comes from burning fossil fuels and, in the air, it oxidizes to form sulfuric acid aerosols. These particles contribute to acid rain and add to fine particulate matter, which can irritate the lungs and harm breathability and visibility. Nitrogen oxides, produced by engines and power plants, drive the formation of photochemical smog; under sunlight they react with volatile organic compounds to create ozone near the ground, which irritates airways and reduces lung function. Tropospheric ozone itself is a harmful pollutant formed by those same reactions, posing health risks and affecting vegetation and climate, even though ozone high in the stratosphere protects us from UV. Particulate matter, especially fine PM2.5 and coarse PM10, consists of tiny particles from combustion, industry, and dust. They can penetrate deep into the lungs, trigger cardiovascular and respiratory issues, and also influence visibility and cloud formation. Together, these pollutants illustrate the key ways air quality is influenced by atmospheric chemistry and particle matter.

The other options describe substances that are either largely inert or not considered primary air-quality pollutants in typical contexts (rarely causing immediate health or visibility issues at ambient levels), or they emphasize water vapor and ordinary atmospheric gases in a way that doesn’t capture the pollutant roles described above.