One of the activities performed by an organization (cutting steel sheet) interacts with the environment through one or more environmental aspects (noise generation). Environmental impacts are the expected and normal outcomes or consequences of an environmental aspect (neighborhood nuisance below legal limits in this case).
Please check risk definition (3.2.10) on ISO 14001:2015 (effect of uncertainty). With environmental aspects and impacts we are considering normal, expected situations. Whenever there is uncertainty there is risk, there is a potential deviation from the expected.
In the example above one of the risks, one of the possibilities, it is a cutting machine malfunction. That malfunction can generate a negative deviation from the expected, can generate much more noise, exceed legal limits and increase neighborhood complaints.
In my work with organizations we determine environmental aspects and impacts. Then, for each impact I ask (and please check the relationship with Mark Hammar’s article):
What can help us improve the environmental impact? (opportunity)
What can deteriorate the environmental impact? (risk)