How do air emissions from pulp and paper mills affect the environment?
Emissions of sulphur dioxide (SO2) and nitrogen oxides (NOX) react with water vapour in the atmosphere, forming small amount of sulphuric and nitric acid. These acids lower the pH of rainwater and thus contribute to the formation of acid rain. Nitrogen oxides also contribute to the formation of excess ozone in the lower atmosphere and the formation of smog. Current levels of particle emissions do not have any significant environmental effects. They may, however, act as carriers for harmful substances, such as heavy metals. Carbon dioxide is a greenhouse gas, contributing to the greenhouse effect. The greenhouse effect is the rise in temperature that the earth experiences because certain gases in the atmosphere (water vapor, carbon dioxide, nitrous oxide, and methane, for example) trap energy from the sun.
