Virtually all industrial activities harm the environment in some way. What varies is how permanent the harm is, and whether and to what degree the harm can be mitigated. We should be especially concerned about harm that builds up faster than it can be repaired (such as the current global warming situation), as well as the use of resources that are not replenished as fast as they are drawn down (e.g. oil, gas, coal). Even "good" activities such as the manufacture of pollution control equipment will consume non-renewable resources and/or introduce harmful byproducts into the environment. Even the end product -- pollution control equipment -- usually only mitigates the harm from other activities, and doesn't actually improve the environment.