One: Poisonous mosquito-repellent incense is made of bhc powder, pesticide 223 and DDT. It can only disperse mosquitoes but not kill them, but its fog is harmful to human health, and frequent use will cause dizziness, nausea and other poisoning phenomena.
Two: Safe mosquito-repellent incense is made of pesticides and other herbs, and its smoke can paralyze mosquitoes' nerves and lead to their death, which is harmless to human health.