Diwali poisoning is due to -
A > CMercury was leading cause of poisioning during mainly due to fire crackers like Pharoa's serpent (black tablet like fire cracker). Phosphorus was second leading cause of Diwali poisioning, but in recent times fire crackers like Pharoa's serpent have fallen in use, this has resulted in Phosphorus being leading of Diwali Poisoning.
Phosphorus
Arsenic
Mercury
Lead