One cannot be too concerned with purification. While the term ‘miasma’ is specifically Hellenic, the idea of ritual purification is not restricted to Hellenic Polytheism. The idea that we should be ritually clean of pollution both physical and spiritual when we go before our Gods is found in many, many polytheistic traditions.
Our Gods deserve the best we can possibly give Them, that includes taking the time to both prepare ourselves for approaching our shrines and for ritual engagement, and being mindful of pollution on an ongoing basis.
If this is too difficult, maybe find another religion that doesn’t have such baseline standards, or a religion that doesn’t give the Gods any thought at all.