The gas that would most readily flow along the ground if accidentally released is typically one that is denser than air. Gases that are heavier than air will tend to settle and move along the ground due to gravity. Examples of such gases include:
- Propane - Heavier than air and can accumulate in low areas.
- Butane - Similar to propane, it is also denser than air.
- Carbon Dioxide (CO2) - Significantly denser than air; it can pool in low-lying areas.
- Chlorine - Heavier than air and can cause harm to health.
In contrast, lighter gases, such as hydrogen or helium, will rise and disperse into the atmosphere. Therefore, in terms of ground-level movement, denser gases are the primary concern for accidental releases.