ETS and related terminology
The terms "ETS", "Second Hand Smoke" and "Passive Smoking": meaning, history, and usage
ETS stands for "environmental tobacco smoke", which is the preferred scientific term for the smoke from burning tobacco in the air. The word "environmental" distinguishes the smoke that is in the air from the concentrated smoke that is intentionally inhaled, a distinction that is obviously important (but absent from other scientific descriptors for smoke, like "diesel smoke", because it goes without saying in those cases). ETS is the combination of smoke from the tip of the cigarette (or the similar smouldering from cigars, pipes, etc.) smouldering when inhalation is not occurring and the fraction of smoke that is exhaled after a smoker takes a puff. When there is need to separate them, which is seldom the case for any practical purpose, the different components can be called "sidestream smoke" and "exhaled smoke", respectively (with the modifier "tobacco" included if there is ambiguity in the context).
However, the latter is also often called "second hand smoke" (SHS) and this term it then often expanded to include all ETS, including the sidestream component. While SHS is a widely used term in popular discussions in American English and often even appears in unbiased scientific analysis, it is not preferred terminology. That is not just because of the ambiguity (about whether it includes the sidestream component) but because "second hand smoke" was a term intentionally created for advocacy purposes. The use of intentionally manipulative terminology is common in the anti-tobacco industry, including among ostensible scientists (see, for example, this discussion in a journal).
"Second hand smoke" is meant to evoke feelings of disgust among those for whom the phrase "second hand" evokes images of poverty, uncleanness, and violations of boundaries. While that built-in bias has largely faded in impact due to the common use of the term, it should still be recognized as being present.
The term "passive smoking" is even more inaccurate scientifically. This term, which refers to the experience of breathing ETS (which is scientifically known as "ETS exposure" or "exposure to ETS"), was originally coined most of a century ago. This was before the effects of smoking were well understood, and so perhaps it represented a genuine misunderstanding about how fundamentally different smoking and ETS exposure are, though even then (or at least when it was first introduced into English), its rhetorical value was presumably intended. In its original German and in some other languages, the term fills the same niche "secondhand smoke" does in American English: it is scientifically inaccurate but sufficiently common that its literal meaning is ignored.
However, use of the term in English, where it is less common, implicitly makes the claim (now known to be false) that ETS exposure is functionally equivalent to smoking. The term "passive" also tends to manipulate people's thinking; though technically defensible as the counterpart to "active", the common uses of the term result in it evoking notions of victimization and helplessness. Because of these connotations, the term has regained popularity as a tool of rhetorical manipulation.
Other terms that have been proposed within the anti-tobacco industry at various times, but have not been widely deployed, include variations on "tobacco smoke pollution" (technically correct, since anything unintentionally put into the environment is pollution, but clearly intended to play on hatred and fears about industrial pollution) or "toxic tobacco smoke" (not really even defensible as literally true, like most uses of "toxic"; anything is toxic in sufficient quantities, but in this case the quantity is defined by context, and that quantity is not toxic).
The use of terms sometimes offers a clue about the bias of the writer or speaker. The use of "environmental tobacco smoke", given that is a bit awkward, usually indicates an effort to be scientifically precise or to avoid political language. In English, use of "second hand smoke" sometimes is intentional rhetoric, reflecting its political origins, but it has become the common popular terminology and thus is often used in writing for a non-technical audience even when no political bias is intended. Similarly, "passivrauchen" (passive smoking) in German is mostly seen as neutral terminology. However, given their technical inaccuracy and colloquial tone, the use of either of these terms in an ostensibly scientific context tends to imply that the writer was interested in popular rather than scientific communication. Use of the more inflammatory terms reflects an attempt to manipulate the reader or listener's opinion using advertising tricks rather than the content of the message.