In an oil spill, does the type of oil matter? If it does, what type of oil causes the most harm?
A. The type of oil definitely matters, because different types of oil behave differently in the environment, and animals and birds are affected differently by different types of oil. However, it’s not so easy to say which kind is worst. We distinguish between “light” and “heavy” oils. Fuel oils, such as gasoline and diesel fuel, are very “light” oils. Light oils are very volatile (they evaporate relatively quickly), so they usually don’t remain for long in the environment (typically no longer than a few days). If they spread out on the water, as they do when they are accidentally spilled, they will evaporate relatively quickly. However, while they are present, they present two significant hazards. First, some can ignite or explode. Second, many light oils, such as gasoline and diesel, are also considered to be toxic. They can kill animals or plants that they touch, and they also are dangerous to humans who breath their fumes or get them on their skin. In contrast, very “heavy” oils (li
