What Crowd Medicine Actually Looks Like — And What to Have Before You’re In It

By Aaron Asay, PA-C, DMSc

I’ve worked mass casualty events. I’ve been the person making triage decisions under conditions that don’t look like a hospital, don’t feel like a clinic, and don’t come with a pause button. What I know from that work is that medical knowledge matters most before the noise starts — because once you’re in the middle of it, there’s no time to look anything up.

This isn’t a piece about any particular crowd or cause. Millions of people have been in the streets this year — at protests, counterprotests, festivals, sports events, political gatherings. Some chose to be there. Some happened to be nearby. Clinically, that distinction doesn’t exist. Exposure determines the injury. Affiliation doesn’t.

Here’s the medical brief I wish existed for the people heading into any large crowd event — and for the family members trying to figure out what ‘be careful out there’ actually means.

What tear gas and pepper spray actually are

These are often called ‘chemical agents’ or ‘gases,’ but the term is misleading. CS gas and pepper spray are both aerosol particulates — they ride on droplets and particles, not as free-floating gas. This matters for two reasons: how to treat an exposure, and what happens when someone comes home.

The first-line treatment is water. Fifteen to twenty minutes of continuous irrigation of the eyes, nose, and mouth. This is not a controversial point — it’s the standard, and it shows up in the clinical literature, in the AAO’s February 2026 statement on ocular exposure, and in every evidence-based first aid protocol for chemical agent exposure. The milk debate that shows up in protest photos? Comparative trials have shown that milk does nothing water doesn’t do — and milk is not sterile. It introduces contaminants to an already-irritated eye. Water is the answer.

Contact lenses must come out immediately after any exposure. Don’t try to wear them through it, don’t try to rinse them in place. They trap particles against the eye and extend the exposure time. Take them out, discard them, don’t put them back in. Glasses don’t have this problem.

Household decontamination is real

Here’s what almost no first aid guide tells you: the agent travels home. Tear gas and pepper spray particles adhere to clothing, hair, and skin. Someone who was exposed and comes home without decontaminating is still off-gassing agent into the house — it will affect anyone who’s there, including children and elderly family members who were nowhere near the event.

Decontamination before entering the house: remove and bag all clothing outside if possible. Shower thoroughly, including hair. Wash all exposed skin. This is basic HAZMAT principle applied at a household level, and it’s genuinely protective.

The stop-the-bleed piece

Kinetic impact projectiles — rubber bullets, baton rounds — are designed to be less-lethal, not non-lethal. A BMJ Open systematic review found that over 3% of documented kinetic impact injuries resulted in death, and more than a quarter caused permanent injury. Head, thorax, and abdomen are the high-concern impact zones. A rubber bullet to the chest is not a bruise you walk off — it’s a chest X-ray conversation. A head impact with any loss of consciousness, confusion, or vision change needs emergency evaluation. Period.

Bleeding injuries at crowd events are typically the same mechanisms as any soft tissue wound: compression works. Direct pressure with a clean cloth, maintained for a minimum of ten minutes without lifting to check, is the field management for most lacerations. Know where the nearest medical station is before you need it.

What to have in your bag

For any large crowd event — whether you’re there intentionally or you’re a bystander:

A rescue inhaler if anyone in the party has reactive airways. Chemical agent exposure can trigger bronchospasm even in people who don’t normally have asthma symptoms. If someone has an asthma history, the inhaler comes.

A glucose source and the medication list for anyone managing a time-sensitive condition. A written list of your medications on paper, in a pocket. A small basic kit: gauze pads, medical tape, nitrile gloves, saline wound wash.

How the Jase Medical Response team thinks about this

I work with Jase because we’re charting the grey areas, making the evidence accessible before the moment of need, and holding a high clinical bar even when the topic is uncomfortable. Riot first aid is exactly that territory — common, predictable, well-evidenced, and almost entirely absent from the professional guidance layer.

Learn more at https://jaseresponse.org/

Aaron Asay, PA-C, DMSc, is a disaster medicine practitioner and PA working with the Jase Medical Response team. This post is for informational purposes only and does not constitute medical advice.