Cigarettes contain over 4,000 chemicals, according to the American Lung Association--many of which are released into the air through second-hand smoke. These chemicals include nicotine, formaldehyde, carbon monoxide, sulfur, turpentine, methoprene, butane arsenic, cyanide, ammonia, lead and tar. Plants may absorb these chemicals through respiration of smoke-laden air, which means that each of these chemicals has an effect on plants.
Plants breathe through pores in their surface, called stomas, which open and close. These stomas are used to absorb water vapor and carbon dioxide and expel oxygen. The way that a plant's stoma pores open and close is determined by two crescent-shaped cells around the opening called guard cells.
The stoma hold water better in a humid environment. This is why greenhouses are kept humid and moist. In desert environments, plants adapt by having fewer stoma or stoma that open infrequently. In an environment laden with cigarette smoke, there is little moisture in the air. This causes the stoma to hold less water, and the plant to dry out, unable to open or close efficiently to get the gases needed to thrive. Additionally, chemicals such as tar, which are present in cigarette smoke, will leave behind a sticky residue, which may also affect the way a stoma may open and close. Bean plants raised in a smoky environment have shown evidence of this failure to thrive in stunted growth.
The chemical vapors in cigarette smoke may further work their way into the soil of a plant, and affect the roots of the plant. Plants rely on their roots to absorb water and moisture. If a plant's roots become coated in chemicals from the soil, they are unable to take in water or nutrients in sufficient quantities. Over time, this can also stunt a plant's growth and lead to a plant's eventual death.