Why is burning off poisonous plants not advisable?

Burning off poisonous plants is not advisable primarily because smoke generated during the combustion process can carry harmful particles over long distances. When poisonous plants such as poison ivy, poison oak, or poison sumac are burned, the smoke contains urushiol, the toxic oil responsible for skin reactions. This smoke can be inhaled or come into contact with individuals nearby, leading to allergic reactions or respiratory issues.

In addition to the immediate health hazards associated with smoke inhalation, the dispersal of toxic particulates can contaminate larger areas, potentially affecting people and wildlife that were not directly in contact with the plants. Thus, the risk of spreading the plant's toxicity through smoke makes burning an ineffective and dangerous method of removal.

Other factors, like the possibility of allergens affecting bystanders or legal restrictions on burning in certain areas, do contribute to why this method is discouraged, but the primary concern lies in the health risks posed by airborne particles.