Clause (3) defines the terms 'law" and laws in force'. The definition is enumerative rather than substantive, i.e. it mentions some of the normal forms in which the law finds its expression. So understood, the definition mention the following as included in the expression 'laws'.
Social awareness about environment is a recent phenomenon. Initially environment referred only to the physical, chemical and biological aspects. Nowadays, it also includes the manmade social, cultural, economic and technological aspects.
The presence of oxygen in the atmosphere is also harmful. For example, corrosion of metals is caused by oxygen. Slow destruction of metals particularly of iron causes a huge financial loss to the society. Oxygen also causes slow degradation of oils and fats.