The moment a wildfire starts near you, you'll get an instant alert and simple tips to reduce your smoke exposure.
30xSmaller than a human hair
Fine enough to reach deep into the lungs. A MERV 13 is built to capture it.
It Doesn't Stay Local
Smoke rides the wind far downwind — you can get smoky air with no fire nearby.
Simple steps to reduce indoor exposure.
During smoke events, the EPA recommends upgrading to a MERV 13 filter — or the highest-rated filter your system can handle — to help reduce the fine particles smoke brings indoors. MERV 13 is the level most home HVAC systems can run while still capturing PM2.5, the fine particulate that makes up the bulk of wildfire smoke.
Over 70,000 wildfires burn in the U.S. every year.
Wildfire smoke can travel 1,000+ miles, affecting states that aren't even near the blaze.
Exposure to wildfire smoke can worsen asthma, trigger heart issues, and lead to ER visits.
Indoor air can hold more fine particles during wildfire events unless it's properly filtered.
The EPA advises using MERV 13 filters or portable HEPA air cleaners during wildfire smoke events.
Use the live wildfire smoke tracker and upgrade your air filters today to protect your lungs and your home.
Shop Filters For Smoke Protection
By Michelle Wan, Brand Manager and Air Quality Writer at Filterbuy · Technically reviewed by David Clark, Licensed HVAC Technician, Filterbuy HVAC Solutions · Published August 16, 2026 · Updated August 16, 2026
Boise’s wildfire smoke usually starts somewhere else. Most Treasure Valley haze rides in on westerly winds from Oregon fires, then gets pinned down overnight by valley inversions, which is why the Idaho fire layer alone will mislead you. Read all three map layers together, and once the AQI passes 100, seal the house and run a MERV 13 with the fan on “On.”
Most Boise smoke is imported on westerly winds from Oregon fires, so the valley can go unhealthy with no local fire burning.
Nighttime inversions make it worse after dark, capping the valley and letting smoke settle back down.
A DEQ advisory is an enforceable burn ban, and the trigger differs by jurisdiction.
MERV 13 is the EPA-recommended filter for smoke, paired with a sealed house, recirculate mode, and one clean room. Stage 1 fire restrictions have covered nine southwest Idaho counties since August 7, 2026.
The map shows three live layers for Boise: active fire detections, the forecast smoke plume, and current AQI at nearby ground monitors, refreshed hourly. Detections come from the EPA AirNow Fire and Smoke Map, plumes from the HRRR model that Idaho DEQ and NWS Boise use, and AQI pins from DEQ’s NowCast network.
The layers rarely agree, and the disagreement is the signal: the plume shows what is coming, the AQI pin what has arrived, the fire layer how long it will keep coming. Most Boise residents check the fire layer first, which is the least useful of the three.
Boise sits downwind, which explains most of its bad air days. Westerly winds carry smoke from central and southern Oregon across the Snake River Plain into the Treasure Valley, so Boise, Nampa, and Meridian can go unhealthy when nothing burns in Idaho. The consequence runs against instinct: in a Treasure Valley smoke event, the map you need is Oregon’s, not Idaho’s.
That was 2026’s pattern: on July 21, NWS Boise tied a Valley smoke event to central Oregon fires with AQI at 167, and DEQ later forecast RED/UNHEALTHY at AQI 180.
Terrain does the rest, because the Valley is a bowl. Afternoon winds stir the air and thin the smoke, but once the sun drops, a surface inversion forms overhead, and everything settles back down, which is why Boise air smells worst at 6 a.m. rather than 6 p.m. The National Interagency Fire Center, headquartered in Boise, counted 6.4 million acres burned nationally in 2026, or 156% of the ten-year average.
Your neighborhood’s AQI sets both the outdoor risk level and the filter your HVAC should be running. Match the map’s pin to the row below; DEQ’s NowCast shortens its averaging window when conditions move fast.
Categories follow the U.S. EPA Air Quality Index. Live Treasure Valley readings come from Idaho DEQ monitors and update hourly.
A number worth knowing: 60. Ada County bans open burning once the AQI hits 60, inside the Moderate band and below where most people notice anything. By setting the legal trigger beneath the perceptual one, the county built an early-warning system more sensitive than the naked eye, which is why Filterbuy treats 60 rather than 100 as the number that sends you to the filter.
A DEQ air quality advisory carries more weight than people assume, because it is an enforceable burn restriction rather than health advice, and the trigger shifts with which side of a city line you live on. Most residents never realize there are three.
Thresholds set by Ada County, Canyon County, and municipal air quality ordinances, administered by Idaho DEQ. Confirm current advisories before burning.
“Open burning” covers campfires and fire pits, burn barrels, weed-control and residential burning, orchard clippings, crop residue, and even fire department training burns. Outside city limits, you also need an Idaho Department of Lands permit during closed fire season, May 10 to October 20.
The practical read: at AQI 74 your wood stove is restricted while a neighbor in unincorporated Canyon County can still legally burn, so check the DEQ burn map first.
Local Tools Worth Bookmarking
AIR Idaho app: free three-day AQI forecast and burn restrictions.
NWS Boise smoke page: the forecasters’ own smoke products.
Idaho DEQ advisories: by county, with the burn map.
Wildfire smoke is dominated by PM2.5, fine enough to slip past the upper airway and settle deep in lung tissue, which leaves the house itself as the intervention. These steps follow EPA guidance, ordered by what Filterbuy sees fail most.
Seal the envelope. Close windows, exterior doors, and the fireplace damper. The Boise instinct is to open up once it cools at night, which is exactly when the inversion pushes PM2.5 back down.
Switch to recirculate. Close any outdoor intake or economizer. Evaporative coolers pull outdoor air straight in, so EPA clean room guidance advises using them sparingly or covering the intakes with 4-inch MERV 13 media.
Install a MERV 13 and run the fan continuously. EPA guidance is to use a MERV 13, or the highest rating your system handles, with the thermostat fan set from “Auto” to “On.” That cuts indoor PM2.5 by roughly half. Find your filter size first.
Build one clean room. Add an ozone-free air cleaner to your bedroom, sized to a smoke CADR of at least two-thirds of the room’s square footage. EPA’s DIY box-fan research recommends MERV 13 media.
Change it more often. Heavy smoke can clog a MERV 13 in 30 to 60 days rather than 90, so check monthly through September or put it on auto-delivery.
A standard 1-inch fiberglass pad rated MERV 1–4 catches lint and little else, leaving it close to useless against smoke. For PM2.5, the jump that matters is to MERV 13, and the Filterbuy guide to MERV ratings covers the scale.
Confirm your blower can handle a MERV 13 before upgrading. Higher static pressure reduces airflow, and reduced airflow across an evaporator coil can cause freezing.
Confirm your blower can handle it, because a MERV 13 in a system built for MERV 8 can raise static pressure enough to cut airflow, and reduced airflow across a coil can freeze it.
From building Filterbuy filters, we know fit matters more than rating. A MERV 13 with a half-inch gap filters less than a well-seated MERV 11, because air takes the easy path around it. That bypass is invisible, and it is the failure we hear about most after heavy smoke.
Filterbuy sees a Treasure Valley smoke event as a demand signal before a weather story, and the pattern never changes: households react to smoke they can see, by which point it has been inside for hours. Smoke arrives on a wind shift, not at a threshold, so the filter must already be in the return.
The panic upgrade is what gets people. Smoke rolls in, they jump from a MERV 8 to a MERV 13 in a system never set up for it, and the blower is fighting static pressure it can’t overcome. Less air moves, not more. On a 100-degree Boise afternoon, that’s how you freeze a coil. Check your filter slot and return sizing first.
David Clark, Licensed HVAC Technician
AQI 167. The Treasure Valley hit the Unhealthy band on July 21, 2026, during a smoke transport event from central Oregon fires.
Source: Idaho DEQ smoke model and NWS Boise forecast.
AQI 60. Open burning becomes illegal in Ada County and incorporated Canyon County cities at that reading, rising to 75 in unincorporated Canyon County, with wood stoves restricted at 74.
Source: Idaho DEQ advisory guidance.
~50%. Running a high-efficiency filter with the HVAC fan on continuously cuts indoor PM2.5 by roughly half.
Source: U.S. EPA, Reduce Your Smoke Exposure.
Wait until the AQI has held below 100 for several hours, and open up in mid-to-late afternoon when mixing is strongest. Avoid the overnight window, because the inversion that forms after sunset is what pulls smoke back down to street level.
Yes, in most Treasure Valley homes, central AC and heat pumps recirculate indoor air rather than pulling it from outside. Keep windows closed, shut off any fresh-air intake, and run the best filter your system safely handles.
A well-fitted N95 or P100 helps above AQI 150 if you must be outside for a long. Cloth and loose surgical masks do not filter PM2.5 and give a false sense of protection.
Roughly June through October, peaking July through September, though one clear day is not the end of it: in 2026, Valley air hit Good and fell back to Unhealthy within 48 hours. DEQ publishes three-day forecasts and notes models are unreliable past 72 hours, so keep the MERV 13 in through October.
The Boise households that come through a bad week comfortably are the ones who bought in June. Filterbuy builds MERV 13 filters in our own U.S. facilities, in 600+ sizes plus custom cuts, shipped factory-direct.
Find your filter size and shop MERV 13 filters or find a custom size for your system. You can also set up auto-delivery for timely filter replacements.
AQI: The EPA’s 0–500 Air Quality Index, converting pollutant concentrations into a color-coded health category. DEQ’s NowCast version shortens its averaging window when conditions move fast.
PM2.5: Particulate matter 2.5 micrometers or smaller, the dominant pollutant in wildfire smoke.
MERV: Minimum Efficiency Reporting Value, a 1–16 scale of filter capture efficiency. MERV 13 is the EPA target for smoke.
Temperature inversion: Warmer air sitting above cooler surface air, capping the Treasure Valley and trapping smoke near the ground.
Subscribe to wildfire smoke alerts for Boise, ID, to get a heads-up before the next event reaches your area.
