The idea behind laying down standards is basically due to the realization that minimal pollution is rather inevitable in the production process. The environment has the capacity to absorb the minimal amount of pollution without any serious adverse impact.
However, if this exceeds a certain limit, then the damage to environment cannot be avoided. The standards are fixed at the threshold, where the pollutants released by the production process do not lead to such a situation. In other words the standards are decided to contain the release of pollutant to the environment and thereby protect the overall quality of environment. In some cases, the standards are industry specific as well as location specific.
A citizen can do much by adopting a code of conduct for himself as per various Environmental Laws and Rules passed by the Central and State Governments to desist from all activity which may pollute the environment.