Your Building Is Breathing Smoke Right Now — Here's What To Do

Published 2026-07-16

The short answer: Chicago's air quality index hit 701 this afternoon — hazardous, and beyond the top of the EPA's standard scale. Your HVAC is pulling that air through whatever filtration you're running right now. In the next 48 hours: cut outside-air intake, upgrade your filters, seal what you can reach, tell your occupants what you're doing, and document all of it. Once the air clears, ductwork and soft goods are the follow-up.

What's happening right now

As of 4 p.m. on July 16, EPA's AirNow put Chicago at an air quality index of 701 — hazardous, driven by PM10 from Canadian wildfire smoke. That is not a number most property managers have trained for. It's a reading that shows up in disaster scenarios, not in July in Chicagoland. But it's here now, and what you do in the next 48 hours makes a real difference for your occupants.

Your HVAC system is pulling that air through whatever filtration you're running right now. Your building envelope is leaking it in through gaps and cracks. Your residents are breathing it. The decisions you make today determine whether this stays manageable or becomes a bigger problem down the road.

The next 48 hours — what actually matters

1. Reduce outside air intake. If you can operate on recirculated air with minimal fresh air, do it now. At this level, that trade-off is the right call. Document that you made this decision and when — screenshot the AQI, note the time.
2. Upgrade your filters today. MERV-13 if your equipment can handle it, MERV-11 minimum. Change them now, not tomorrow. This is the single fastest way to stop particulate from loading into your system and ductwork.
3. Seal what you can reach. Outdoor louvers, gaps around ductwork, dampers pulling outside air. Quick wins that reduce infiltration.
4. Tell your occupants what you're doing. Don't minimize the situation. Don't catastrophize either. "We've reduced fresh air intake and upgraded filtration because outside air is hazardous. We're managing exposure and monitoring conditions." Most people just need to know you noticed and you're acting.
5. Keep track of what happens. Note any resident complaints — odor, visibility, health concerns — with times and locations. Take photos of filters when you change them. This tells you whether the problem is getting worse or better, and it helps if you need professional help.

After the air clears — the follow-up work

Once the AQI improves, particulate that settled in your ductwork will keep getting re-entrained. Duct cleaning is the standard move. Coil cleaning too — loaded coils reduce efficiency and harbor contamination. If you run a preventative maintenance program, this belongs in it.

If odor persists in corridors or units, that's a sign soft goods need attention. Carpet, upholstery, and finishes can hold smoke compounds long after the outside air is clear.

If you need help figuring out what comes next

This is exactly the kind of situation we handle. If you're watching this event unfold and you're not sure whether your building needs professional cleaning, duct work, remediation, or just a walkthrough to assess what actually happened — that's a call worth making. We've worked through these events before and we know what matters.

Frequently asked questions

What AQI level is hazardous for building occupants?

Anything above 300 falls into the EPA's top category — hazardous — where health warnings apply to everyone, not just sensitive groups. The standard index only runs to 500; Chicago's 701 reading on July 16 was beyond the scale entirely. At those levels, reduce outside-air intake and upgrade filtration immediately.

Should I shut off my HVAC during a smoke event?

Usually no. You want air moving through filtration. The right move is to reduce or close the outside-air intake and run on recirculated air with the best filter your equipment can handle. Shutting the system off entirely leaves you with no filtration at all while smoke still infiltrates through the envelope.

What MERV filter do I need for wildfire smoke?

MERV-13 if your equipment can handle the static pressure, MERV-11 at minimum. Change them during the event, not after — filters load fast at hazardous AQI, and a loaded filter stops doing its job and strains the system.

Do I need duct cleaning after a wildfire smoke event?

If your building pulled in hazardous air for an extended period, likely yes. Particulate that settles in ductwork gets re-entrained every time the system runs. Coil cleaning matters too, since loaded coils reduce efficiency and harbor contamination.

How do I know if my building needs professional help?

Persistent odor, visible particulate, or resident complaints after the outside air clears are the signals. A walkthrough assessment tells you whether you need duct and coil cleaning, soft-goods remediation, or nothing at all.

Fairvest Restoration & Construction answers 24/7. Talk to us, call (630) 474-5128, or email kurt@fairvestco.com.

— Kurt Fairless, Founder & President. AQI reading via EPA AirNow, Chicago reporting area, 4 p.m. CDT July 16, 2026. Conditions change quickly during a smoke event; check AirNow for current readings.