Could fans be burning oil these days?

For a number of years now, I have found myself getting all coughy and harumphy after sitting in front of a fan for any significant period of time. The longer this duration, the longer lasting and more dramatic the effect. It doesn't seem to happen when the fan is new, but give it a year and it starts to become this way. I was wondering if others with sensitive respiratory systems may also be noticing such a pattern. Anyone notice this? Thanks for sharing your thoughts, anecdotes, and observations on this. What follows are my own.

I've had a number of years to think about the cause. The only one that seems to persist is that lubricant (motor oil) is being heated up by the motor. If I put my hand on the motor housing, it can feel quite warm, which means the motor itself is significantly warmer. Maybe an internal seal breaks with time and lubricant starts to leak. Or maybe the seal gets less effective in warmer temperatures (if the prevailing temperature is high, then the motor can be expected to be that much hotter). Or maybe there isn't even a seal. I believe that occasionally, I can even smell traces of what seems remotely like diesel. For some of the cheaper fans that I unwisely kept for a long time, this smell can be quite pronounced.

It doesn't seem to matter what brand or type of fan I buy, they all have this pattern. Then again, I strongly suspect that regardless of the quality of the fan, the motors are probably made in the same country these days. I don't recall having such a problem with fans in my younger decades (though I wouldn't necessarily have noticed).

Coughing due to fans is often attributed to invisibly fine dust, but I can confidently say that it is not the cause in this case. The problem persists even if I've ventilated the room for hours under conditions of aggressive air blowing fans. It also persists when I use fans in an unventilated but HEPA air-filtered room.

Coughing due to fans is also often attributed to the drying out of one's respiratory passages. I can see this as a contributing factor. In the absence of a fan, when one exhales, the moist air lingers around in front of one's face and mixes with the air that is inhaled in the next breath. The inhaled air is not as dry as in the rest of the room. If there is a constant breeze, then there is not as much lingering exhaled air to mix with the air that is inhaled for the next breath. I suspect that this is the drying out effect. Empirically, I find that oscillating the fan reduces the respiratory aggravation, and I think it is because there is no drying out effect when the fan is pointing away from me (and no cooling, either). However, there is *some* respiratory aggravation that results. I can also say that the drying out effect is not the sole cause of the respiratory aggravation because if it was, then I should also have the same problem in riding in a car with the windows down.

Again, thanks for sharing what you may have noticed about this in your own lives, any thoughts on plausible causes, and (in particular) any solutions (e.g. what fan name brands have you found to be least problematic?).