Droplet or Airborne: Distance, Filter, and the Door
One patient room cut vertically into two halves: left, mid-size droplets on a falling arc ending inside a labeled separation radius; right, fine particles rising to a ceiling exhaust behind a closed door with a gauge reading negative.
| DROPLET | AIRBORNE | |
|---|---|---|
| Particle behavior | Large respiratory particles that arc and settle | Droplet nuclei and small particles that stay suspended |
| How far it travels | A short distance, then falls out of the air | Rides air currents through the room and beyond the doorway |
| Room | Single room preferred; cohorting permitted with the spatial separation the guideline states, currently at least 3 feet between patients, with the privacy curtain drawn | Airborne infection isolation room: negative pressure relative to the corridor, the guideline's stated air changes per hour, air exhausted directly outdoors or high-efficiency filtered before recirculation |
| Door | May remain open | Stays closed, every time, including during care |
| Staff respiratory protection | Surgical mask donned on entry | Fit-tested respirator with a user seal check at every use |
| Patient in transport | Surgical mask on the patient | Surgical mask on the patient, never a respirator; skin lesions covered |
| Who may be assigned | Any competent staff member | For measles and varicella, only personnel with documented evidence of immunity |
| Representative organisms | Influenza, pertussis, mumps, rubella, Neisseria meningitidis meningitis, group A streptococcal pharyngitis during the first day of therapy, pneumonic plague | Tuberculosis, measles, varicella, disseminated zoster, smallpox |
| The trap | Assuming the door must close, or that a respirator is needed | Accepting a surgical mask, or leaving the door open for a moment |
The trap row
- Varicella and disseminated zoster are airborne plus contact. Two categories, both in force.
- Smallpox is airborne plus contact.
- Localized zoster with covered lesions in an immunocompetent host stays on standard precautions. The lesion count and the host, not the virus name, decide.
Memory hookFour that float: tuberculosis, measles, varicella, zoster that spread.
Watch outA surgical mask is not respiratory protection against an airborne organism. Entering a tuberculosis room in a surgical mask is an exposure, and no later action undoes it.
Margin noteThe door is part of the PPE.
TakeawayDroplets fall and a mask suffices. Nuclei float, and only a fitted respirator behind a closed negative-pressure door suffices.
Verify at reprint: the exact spatial separation wording, the negative-pressure specification, and the air changes per hour against the current CDC/HICPAC isolation precautions guideline. Verify fit testing and user seal check against current OSHA respiratory protection requirements. Removal order and removal location are on page 8.