The magnitude of toxic surface runoff
With climate change, increased rainfall and urbanisation in full force, the ‘unspoken’ pollution and toxicity of highway rainwater runoff is coming to surface. Toxic and poisonous pollutants such as PAHs (Polycyclic Aromatic Hydrocarbons) and metals which are emitted from vehicle exhaust, tires, brakes and more are very harmful to not only the environment, but also our health. With the increased rainwater, these toxins are polluting the rainwater surface runoff from roads and highways which inevitably enters the soil and the environment.
Until recently, toxic surface runoff caused by pollutants was mistakenly considered a natural occurrence as it is caused by rainfall. Essentially, this means that very little has been done to prevent and monitor toxic surface runoff from entering the environment and no action is being taken to reduce the pollution. However, in light of climate change, an attitude shift to greener behaviours and recent studies, the importance of addressing the toxic surface runoff is now considered paramount.
Recent research has found that some surface runoff water from highways is way above the legal limits for copper, zinc and lead and is entering the soil without any consideration. In 2018, there were 533 serious cases of toxic surface rainwater runoff reported, and this is only expected to rise with increased rainfall expected to come.