Atmospheric concentrations refer to the amount or quantity of a substance present in the Earth's atmosphere. This can include gases, particles, and other pollutants that are suspended in the air we breathe. The concentration of these substances can vary depending on factors such as location, altitude, weather conditions, and human activities. Atmospheric concentrations are often measured using scientific instruments and techniques to determine the levels of specific contaminants or pollutants in the atmosphere. These measurements help scientists understand how human activity is affecting air quality and can inform policy decisions related to environmental protection.