They detect visible airborne particles, and thick vapour clouds can scatter light in the same way smoke does
Experimental, immunologic, and systems-level studies indicate that cigarette smoking promotes immune phenotypes resembling accelerated aging, including contraction of nave lymphocyte pools, expansion of senescent T-cell populations, disruption of regulatory signaling pathways, and persistent remodeling of adaptive immunity
So while smoking might help with appetite control, it can also lead to less favorable fat storage patterns that come with higher health risks
Yang, Littered cigarette butts in both coastal and inland cities of China: occurrence and environmental risk assessment
[107] In June 2019, San Francisco banned the sale of e-cigarettes
Shes been incredibly open about cannabis use, including lighting what appeared to be a joint on stage at the 2013 MTV Europe Music Awards