Study Finds ‘Thirdhand Smoke’ a Hidden Threat Inside Buildings

Beijing — A new study published in the scientific journal Building and Environment highlights “thirdhand smoke” as an increasingly persistent and complex threat to indoor air quality.

Researchers from the Institute of Atmospheric Physics under the Chinese Academy of Sciences have, for the first time, conducted real-time analyses of thirdhand smoke. Their findings show that toxic residues from tobacco smoke can remain indoors and undergo chemical changes long after smoking has stopped.

Thirdhand smoke refers to toxic substances left behind by tobacco smoke that cling to indoor surfaces such as walls, furniture, carpets, and curtains. Unlike secondhand smoke, which is inhaled directly from the air, thirdhand smoke becomes embedded in indoor environments. The study indicates that it is not merely a static stain but a dynamic source of pollution, continuously re-emitting particles and gases back into the air and undergoing chemical transformations over time.

Using advanced air-quality monitoring technologies, the research team traced the release of fine particles and gases from contaminated surfaces. This led to the identification of key differences between secondhand and thirdhand smoke. While secondhand smoke particles disperse relatively quickly, thirdhand smoke persists at low levels indoors for extended periods. Moreover, the chemical composition of re-emitted thirdhand smoke particles becomes increasingly complex, with rising nitrogen content over time suggesting the formation of more harmful compounds.

The study also points to the influence of household materials on chronic thirdhand smoke contamination. Porous materials such as wool carpets and upholstered furniture act as effective reservoirs, absorbing tobacco-related chemicals and slowly releasing them back into the air. This process makes thirdhand smoke highly resistant to conventional ventilation, allowing contamination to persist for hours or even days after a single smoking event.

Sun Yele from the institute said the findings provide important scientific evidence for shaping public health guidelines. They underscore the need to incorporate thirdhand smoke into tobacco control policies and indoor air quality standards, and introduce new chemical indicators to detect lingering, often overlooked contamination posing a major challenge to maintaining healthy indoor environments.

Source: www.xinhuathai.com