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
Published August 23, 2026 | Updated August 23, 2026
Check the AirNow Fire and Smoke Map first, since it plots active fires, smoke plumes, and ground-level PM2.5 on one screen. Confirm your neighborhood number on the South Coast AQMD map, and take evacuation orders only from Riverside County Emergency Management. Once the AQI passes 100, close the house, switch the HVAC fan from Auto to On, and run the highest efficiency filter your system can safely handle.
AirNow is the primary live source, South Coast AQMD gives the neighborhood reading, and Riverside County issues evacuation orders.
Moreno Valley sits in the South Coast Air Basin, where an inversion layer traps smoke at ground level, and haze is worst at dawn.
The EPA recommends MERV 13 or higher during smoky periods, replaced once the media looks dark brown or black.
Fires along Gilman Springs Road, Reche Canyon, and the Badlands can put smoke over the city within an hour.
Apartments and window unit homes have no filter slot and need a portable air cleaner and a clean room.
Four official sources cover live conditions, and order matters. Start with the AirNow Fire and Smoke Map to see whether a fire is local or the smoke is drifting in, confirm the number on the South Coast AQMD neighborhood map, then take evacuation orders from Riverside County Emergency Management, the only authority on them.
Sensors update faster than forecasts, and the Springs Fire shows the gap.
Times and acreage from the CAL FIRE Springs Fire incident record.
Acreage and times from the CAL FIRE Springs Fire incident record. The Riverside, CA wildfire and smoke map often shows the same plume first.
Moreno Valley sits in the eastern South Coast Air Basin, a 6,600-square-mile bowl where low wind and a persistent inversion layer trap pollutants near the ground. Smoke that settles overnight stays until the following afternoon, which is why haze is worst at dawn. Santa Ana conditions reverse the pattern, funneling dry offshore wind through the San Gorgonio Pass and across the Badlands, which puts the fastest fires east of the city.
A county-wide grade is not a neighborhood reading. Riverside County failed all three American Lung Association measures in State of the Air 2026, and South Coast AQMD notes that the county figure blends the Coachella Valley with the South Coast basin. Let the sensor nearest your street decide what you do today. The same conditions keep the Inland Empire near the top of U.S. cities with the worst and best air quality.
Regional forecasts treat Riverside County as one unit, and Moreno Valley does not behave like one. Filterbuy built this breakdown because each approach produces a different smoke pattern, and knowing which is burning tells you how much warning you have.
Filterbuy's synthesis of documented fire activity and basin wind behavior. A planning aid, not a forecast.
Two corridors have documented ignitions. The Springs Fire started on Gilman Springs Road on April 3, 2026, and reached 4,176 acres, with evacuations in Rancho Bellagio and Moreno Valley Ranch. The Rabbit Fire burned 8,355 acres from that corridor in July 2023, and the Reche Fire took 437 acres that afternoon. This is Filterbuy's synthesis, not a forecast, so defer to the CAL FIRE incident list and the county live incident feed for perimeters and evacuation orders.
The Air Quality Index runs 0 to 500, and in a wildfire event the driving pollutant is PM2.5. If ozone is running higher than particulates, the number may describe ozone and not smoke, so check the pollutant name and match it to the right MERV rating for a high AQI day.
Six EPA categories grouped into four filtration responses, since the indoor action does not change above 200.
The first hour after a plume appears is when a house can still be sealed before indoor particulates match outdoor levels. These steps run in order of impact, so air purifiers come last.
Confirm the source. Check the fire and air quality maps before assuming the smoke is local.
Seal the envelope. Close windows and exterior doors, then shut off any evaporative cooler or whole house fan. Both pull outdoor air inside by design and undo everything else here.
Switch the fan to On. Cycling indoor air through the filter continuously beats any other setting.
Suspend indoor sources. Skip candles, unvented gas cooking, and outdoor exercise.
Check the filter. If the media is gray, brown, or black, replace it now. Keep spares, since availability tightens once a fire burns.
The EPA recommends MERV 13 or higher during smoky periods and notes most systems accommodate it when the filter is changed often. MERV, rated under ASHRAE Standard 52.2, measures how well a filter captures particles between 0.3 and 10 microns, and wildfire smoke is dominated by PM2.5.
MERV 13 is not equivalent to True HEPA. Confirm static pressure with a licensed technician before upgrading.
A MERV 13 pleated filter is not True HEPA, which is built for sealed portable air cleaners with a dedicated fan. The practical setup is MERV 13 in the central system with a portable HEPA cleaner in the bedroom, after a technician confirms static pressure. Filterbuy makes MERV 13 pleated filters in more than 600 standard sizes, so the limit is usually what the system can handle. See Filterbuy's guide to MERV 13 compared with True HEPA.
Apartments, condos, and homes with window or wall units have no filter to upgrade, and the washable screen in a window unit is a dust guard for the coil, not a PM2.5 filter. In those homes, a portable air cleaner is the whole system, so size it to one room, put it where you sleep, and leave it running. Build one clean room with the door shut and weatherstrip the gaps. Renters with central air should ask the property manager for the filter size before smoke season.
The failure I find most on Inland Empire service calls is not the wrong MERV rating. It is a filter seated backward, or a slot that never sealed. A MERV 13 with a half-inch gap around the frame moves unfiltered air past the media and performs worse than a clean MERV 8 that fits. Check the airflow arrow and the gasket first.
David Clark, Licensed HVAC Technician, Technical Reviewer
The EPA recommends a filter rated MERV 13 or higher during smoky periods and notes most systems accommodate one when it is replaced frequently, per EPA guidance on preparing for smoke and heat.
South Coast AQMD publishes AQI values at 1,218 locations by blending regulatory monitors, low-cost sensors, and a forecast model, per South Coast AQMD current air quality data, verified August 2026.
Riverside County ranked second nationally for ozone and tenth for daily and annual particle pollution, failing all three measures on 2022 to 2024 data, per the American Lung Association's State of the Air 2026 report card for Riverside County.
Incident status changes by the hour. CAL FIRE publishes locations, acreage, and containment for Riverside County, and county emergency management posts evacuation orders, so check both before concluding.
Smoke travels a long way. Fine particulate matter drifts hundreds of miles on prevailing winds, and the inversion layer traps it at ground level, so a smoke smell with no local fire usually means drift smoke settled in overnight. Either way, the response is the same, which is to keep wildfire smoke out of your house.
Go by inspection, not the calendar. EPA guidance is to replace the filter when it looks dirty, meaning dark brown or black, and under heavy smoke, that arrives well before the interval on the packaging.
A well-fitted N95 or KN95 respirator is the only common mask that meaningfully reduces PM2.5 exposure. Cloth and surgical masks do not seal and offer little protection. Respirators also do not fit small children or seal over facial hair, so indoor filtration remains the primary protection.
AQI, Air Quality Index. A 0 to 500 EPA scale translating pollutant levels into public health categories.
PM2.5, Fine Particulate Matter. Airborne particles 2.5 microns or smaller, the main component of wildfire smoke, small enough to reach deep lung tissue.
MERV, Minimum Efficiency Reporting Value. An ASHRAE 52.2 scale for how well a filter captures particles from 0.3 to 10 microns.
Drift Smoke. Smoke carried well away from an active fire by wind, often prompting an official advisory where there is no local fire.
Smoke rarely gives this valley notice, and the households that ride it out are the ones with a clean, correctly rated filter already in the return. Measure your slot today, then shop MERV 13 air filters made in the USA at Filterbuy's own factories, or build custom air filter sizes to the quarter-inch. Better air for all starts at the filter.
Subscribe to wildfire smoke alerts for Moreno Valley, CA, to get a heads-up before the next event reaches your area.
