What is a notable physical property of sulphur dioxide?

Sulphur dioxide is best characterized as a colourless gas that possesses a pungent, distinctive odor, which can be quite irritating to the respiratory system. This property is particularly significant because it can be easily detected at low concentrations, making it important for safety and environmental monitoring. The pungent smell is often likened to the odor of burnt matches or rotten eggs, stemming from its chemical structure and the presence of sulphur. Thus, the description of sulphur dioxide being colourless with a pungent smell accurately reflects its physical and sensory characteristics. This property is crucial in both industrial and natural contexts where sulphur dioxide may be present, such as in volcanic eruptions and various industrial processes.