In my view, is a departure of Old Testament Passover which was bloody with a lot of discrimination undertaking. In a New Testament, our bodies are Temple of God that why Catholics me included, ash is smeared on our fore-head to shield us from looming evil one on mission to put Jesus into temptation-unlike blood in old testament that shielded Israelite from God killing of firstborn .
Ash is from plants,hence no killing involved. But in old testament both livestock and human were killed. And definitely heaven there will no killing.