The safer way to remove rodent debris from a vehicle is vacuuming it up instead of scattering it with a compressed air nozzle.
Critters such as mice, rats, chipmunks and squirrels may find their way into various areas of a vehicle. Here, I'll focus on the air filter housing — sometimes called the filter box — located in the engine compartment.
It's not uncommon for technicians to find rodent-related debris inside an engine's air filter box during a routine air filter replacement. Other times, the technician finds it while visually inspecting an air filter for clogging.
This occurs while troubleshooting a symptom of a sluggish-running engine.
The more obvious clue of rodents is a nest of some kind inside the filter box. Perhaps you haven't encountered this condition yet, but experience has shown that critters may create nests from a variety of materials such as straw, sticks, twigs, grass, paper scraps, etc.
Dried droppings — rodent fecal matter — may be much less obvious to the naked eye. Based on my own field experience, these droppings tend to be small black beads that may be overlooked.
For one thing, the black droppings may blend in with other dirt inside the air filter box. For another, they may not stand out very clearly against the background of the black or dark-gray color of the air filter box itself.
Suppose a tech removes an old air filter and discovers debris in the bottom of the air filter box. (The accompanying photograph shows the bottom of a common Honda Accord air filter box.)
Often, the tech blows out debris with compressed air and an air nozzle. Although the air nozzle displaces the dirt effectively, it also scatters it into the air. A careless tech could breathe some of that airborne dirt — perhaps get some in his eyes.
On the one hand, plenty of techs have blown out the dirt and gotten away with it. On the other hand, I suspect any medical professional would discourage scattering any kind of rodent feces in the air.
I also suspect that a doctor would call "scattering" a risky maneuver — at best.
Please consider some sensible, easy precautions when cleaning out an air filter box. First, wear a face mask or impromptu bandana. At the same time, turn your face away from the work area while operating the air nozzle. Work quickly.
Second, I have mentioned use of a shop vacuum cleaner in previous columns. (This is the roll-around style of vacuum cleaner popularized by Shop-Vac Corp. and other manufacturers.)
Vacuuming out the rodent droppings may not be a perfect solution, but I suggest that it's substantially less risky than creating a cloud of fine, potentially toxic dirt in your work area.
Third, some techs I work with keep a fine-bristle brush handy — perhaps an old paint brush. Where necessary, they carefully dislodge any dirt inside the filter box with the brush first. Then they vacuum up the loosened dirt with the shop vacuum.
Practical experience with a shop vacuum and small brush indicates that the method may add a minute or so to an air filter replacement job. So, I'm not recommending a time-consuming alternative to the air nozzle method.
Granted, the risk of getting a nasty infection from rodent feces may be relatively small. That said, however, it takes little effort to eliminate or minimize this risk.