Alberta Boilers Safety Association (ABSA) Practice Test

Sulphur oxides in flue gas are considered undesirable primarily because they contribute to acid rain. When sulphur dioxide (SO₂) and sulphur trioxide (SO₃) are released into the atmosphere, they can react with water vapor, oxygen, and other compounds to form sulfuric acid (H₂SO₄) and sulfurous acid (H₂SO₃). These acids, when mixed with rainwater, result in acid rain, which can have a profound negative impact on the environment.

Acid rain can lead to the deterioration of buildings and monuments, damage aquatic ecosystems, and harm vegetation. Additionally, it can leach harmful heavy metals from the soil into waterways, further exacerbating environmental damage. Therefore, controlling the emissions of sulphur oxides from combustion processes is crucial for minimizing their harmful effects on the environment and human health.

While the other options touch on related concepts, they do not encapsulate the main environmental and ecological impact associated with sulphur oxide emissions.