Thirdhand smoke is the toxic residue of tobacco smoke that remains on surfaces long after the cigarette is finished- persisting for months to years, and containing carcinogenic compounds that continue forming through ongoing chemical reactions.

Through specific interventions for each surface because smoke odor is not surface contamination that wipes off, but chemical compounds bonded to materials that require active neutralization and removal.

Gutka and most smokeless tobacco products do not produce secondhand smoke in the conventional sense, but they produce secondhand exposure through spitting, handling, and environmental contamination that carries its own documented risks.