CS at a glance
- Physical form
- A white crystalline solid, released as a smoke or fine dust
- How it irritates
- Contact with moist tissue: eyes, nose, throat, lungs and sweaty skin
- Where it ends up
- Horizontal surfaces, carpet, upholstery, bedding, closets, return air ducts
- Does it fade by itself?
- Not reliably in a closed home; plan on physical removal
- What revives symptoms
- Foot traffic, sitting on furniture, making beds, furnace or AC airflow, warmth and humidity
Why a powder behaves differently from a smell
Most canisters used by law enforcement burn or blast a payload that turns CS into an aerosol. Inside a house the particles drift with air currents, then fall out onto floors, tabletops, window sills and the tops of cabinets. Some pass through door gaps and settle in rooms nobody thought were affected. Fabric acts like a filter and traps a surprising amount.
A smell is a gas, and it leaves when the air is changed. A deposit of particles does not. Opening windows clears the haze but leaves the dust in place, which is why families often feel better on day one with the windows open and worse on day four when they close up the house, turn on the heat, and start using the couch again.
Older northwest Denver homes add a twist: plaster walls with fine cracks, wood floors with gaps between boards, and floor registers that open straight into ductwork. Each of those is a place where powder can hide and come back out later.
How removal generally works
These are the broad stages a careful cleanup follows. They are a guide for understanding a scope of work, not a do-it-yourself recipe for a heavily gassed home.
Ventilate without stirring
Air moves out of the house through windows with fans exhausting outward, while people avoid sweeping, shaking rugs or running a household vacuum that blows fine dust back into the room.
Capture dust with HEPA filtration
Loose powder is collected with HEPA-filtered vacuums and air scrubbers so particles are trapped instead of recirculated.
Wash surfaces top down
Walls, trim, fixtures, counters and floors are wiped with detergent solutions and rinsed, starting high and finishing low, changing cloths often so residue is not spread.
Sort fabrics and porous items
Washable items are bagged for laundering; heavily dosed mattresses and cushions are evaluated for cleaning or disposal.
Deal with the air system
Filters are replaced and ducts are evaluated, because a return register can pull a large share of a room's dust into the system.
Common questions
Why do my eyes burn more when the sun hits the living room?
Warmth and humidity seem to make residue more irritating, and sunlight warms surfaces where dust settled. It is a sign residue is still there, not that the gas is coming back.
Is the white film on the window sill tear gas?
It may be. A powdery film on dark or smooth surfaces after police used CS is a common sign. Wear gloves and avoid wiping it dry, which spreads it.
General information for Berkeley, not a quote or professional advice. In an emergency, call 911.