Ask Lemmy

That is simply not correct in any way, shape, or form.

https://www.nature.com/articles/ni.3069

In addition to housing an extensive retinue of cells of the adaptive immune system, the lungs have other critical defensive abilities provided by the respiratory epithelial cells. Whitsett and Alenghat describe how the respiratory epithelium juggles its role as the surface of gaseous exchange with its ability to actively combat infectious agents and harmful particulate matter. On its most basic level, the epithelium represents a physical barrier that produces mucus, which entangles and sweeps away damaging agents via the action of the mucus 'escalator'. However, even surfactant proteins, which are involved mainly in diminishing surface tension, 'moonlight' as antimicrobial molecules and are able to opsonise bacteria. The respiratory epithelium is also able to directly sense pathogens and respond via the release of antimicrobial peptides or signal escalation of the immune response through their production of the cytokines TSLP, IL-25 and IL-33. Collectively, these innate processes are usually able to maintain near-sterility of the lungs without the intervention of 'conventional' cells of the immune system.

It's not necessarily "more dangerous" to breathe pathogens than consume them, the issue with evaporative humidifiers is that they don't get cleaned as much as they should so the bacteria keep growing and growing and spraying more and more into the air until they overwhelm your immune system and make you sick. By contrast, you eat something bad and it's one and done and out of your system (usually, assuming it's not really nasty).