When wildfire smoke rolls into Tigard, it can feel like you’re fighting a battle you can’t see. You want to keep your home comfortable and safe, especially if you have children, older adults, or anyone with asthma or heart conditions. The good news is you can cut smoke exposure indoors with a clear plan, the right filters, and a few simple upgrades. In this guide, you’ll learn exactly how to set up your HVAC and portable filters, what to buy, and when to act so your indoor air stays cleaner on smoky days. Let’s dive in.
Why wildfire smoke matters in Tigard
Tigard and surrounding Washington County communities can see periodic smoke in late summer and early fall. Wildfire smoke contains fine particles called PM2.5 that are small enough to reach deep into your lungs. That’s what drives most of the short- and long-term health risks.
Two helpful benchmarks guide your targets. The EPA 24-hour standard for PM2.5 is 35 µg/m3, which is a good upper limit for short-term exposure at home. The annual benchmark is 12 µg/m3, which is the ideal indoor target when conditions allow. During smoke events, outside air can push indoor levels higher unless you prepare your home and system.
Your indoor air game plan
You can reduce smoke indoors with a layered approach. Focus on filtration, air sealing, and smart HVAC operation. Then monitor and adjust so you stay below your target levels.
Start with filtration basics
- In-duct filter: Use the highest efficiency your HVAC can handle. Aim for a MERV-13 filter if your system is compatible. It captures far more fine particles than common MERV-8 or MERV-10 filters.
- Portable HEPA air cleaners: A true HEPA removes at least 99.97% of particles at 0.3 microns in a single pass. These shine in bedrooms, home offices, and living rooms when sized correctly.
- Corsi-Rosenthal box: A DIY box fan plus four 20-inch MERV-13 (or MERV-11) filters. It is an affordable, effective supplement in key rooms.
Make MERV-13 work for your system
A MERV-13 filter adds resistance to airflow. Many modern systems can handle it, but older blowers may struggle. Before upgrading, have a qualified HVAC technician check static pressure and blower capacity.
If needed, a thicker MERV-13 media filter or a high-efficiency ECM blower can maintain airflow. During smoke events, set your fan to ON so air recirculates through the filter continuously. If your system brings in outdoor air, close or minimize that intake when outside air is smoky.
Size portable HEPA units correctly
Getting the right size is the difference between “nice to have” and “this really works.” Use CADR, the clean air delivery rate, to match a unit to your room.
- Target 4 to 6 air changes per hour for a clean room during smoke events.
- CADR formula: CADR needed (cfm) = room volume (ft3) × ACH ÷ 60.
- Example: A 12 × 12 × 8 ft bedroom is 1,152 ft3. At 5 ACH, you need about 96 cfm. Choose a unit with a CADR at or above that number.
Practical tips: Place units where airflow is not blocked. Consider a quiet mode for nights, and step up to a higher speed when you’re away. Replace prefilters and HEPA cartridges per the manufacturer, especially after heavy smoke.
Use Corsi-Rosenthal boxes wisely
A well-built Corsi-Rosenthal box can rival mid-range HEPA units for a fraction of the cost. Use fans with fused plugs and avoid leaving them unattended for long periods. Noise can be higher, and filters load quickly during heavy smoke, so keep replacements handy.
Create a clean room
Pick one bedroom or a home office as your clean room. Seal it as well as practical and size a HEPA unit for 4 to 6 ACH. Close doors and run the unit continuously during bad smoke. If someone in your household is vulnerable, prioritize this space.
Tighten the envelope: simple air sealing
Reducing leaks slows smoke entry and helps your filters do more with less. Start with the basics:
- Weatherstrip exterior doors and install or repair door sweeps.
- Caulk gaps around window frames and any penetrations for pipes or wires.
- Add low-profile threshold seals on sliding glass doors.
- Close fireplace dampers and the flue when not in use.
- Check window seals. For older single-pane windows, consider temporary plastic sheeting during heavy smoke.
Do not over-seal if you have combustion appliances. Maintain working smoke and carbon monoxide detectors so your home stays safe.
Run your HVAC the right way during smoke
- Fan mode: Set to ON to recirculate air through your filter.
- Outdoor air dampers: Close or set to minimum. Avoid bringing smoky air inside.
- ERV/HRV: Most units should be turned off or reduced during heavy smoke. Check your manufacturer guidance.
- Ducts: Seal visible leaks with mastic or foil HVAC tape. Tight ducts improve filtration and reduce infiltration.
Monitor and adjust in real time
Use official air quality sources to decide when to act. When the AQI rises above 100, start protective measures. Above 150, tighten up and maximize filtration. At very high levels, focus on your clean room and consider relocating vulnerable people if indoor air cannot be kept within targets.
Indoors, a consumer PM2.5 sensor helps you see what’s working. Aim to keep indoor PM2.5 below 35 µg/m3 during events. If possible, stay below 12 µg/m3. If levels stay high, add filtration, reduce leaks, and retreat to your clean room.
Pre-season checklist for Tigard homes
- HVAC service: Schedule a spring or early summer visit to check blower, belts, motor function, and static pressure before upgrading to MERV-13.
- Stock up:
- Spare MERV-13 filters if your system can handle them.
- One or two portable HEPA units sized for bedrooms and your main living space.
- Materials for air sealing: weatherstripping, door sweeps, caulk.
- Replacement filters for any HEPA or Corsi-Rosenthal units.
- Detectors: Test smoke and carbon monoxide detectors and replace batteries.
- Clean room plan: Choose the room, measure it, pick your ACH, and calculate the CADR.
CADR quick template you can use
- Step 1: Measure room volume = length × width × height.
- Step 2: Choose 4 to 6 ACH for smoke events.
- Step 3: CADR = room volume × ACH ÷ 60. Round up and select a unit at or above that CADR.
Example: 12 × 12 × 8 ft = 1,152 ft3. At 5 ACH, CADR ≈ 96 cfm.
What to do during a smoke event
- Close windows and exterior doors. Add temporary sealing if you feel drafts.
- Set HVAC fan to ON. Confirm outdoor intakes are closed.
- Run portable HEPA units in bedrooms and your main living area. Use the right CADR.
- If you have Corsi-Rosenthal boxes, place them centrally with clear airflow.
- Monitor indoor PM2.5. If levels remain high, add another filter, reduce leaks, and move vulnerable people to your clean room.
- Limit indoor particle sources: cooking, candles, and vacuuming without a HEPA filter can spike PM2.5.
- Replace filters promptly after heavy smoke. Loaded filters are less effective and can produce odors.
After the smoke clears
- Replace or clean filters used during the event, following manufacturer guidance.
- Inspect your HVAC for soiling. Consider professional duct cleaning only if needed and recommended by your technician.
- Restock supplies and update your clean room and maintenance plan.
Maintenance that fits your HVAC routine
- Annual tune-up in spring: blower and controls inspection, static pressure check, and MERV-13 compatibility review.
- Filter schedule: Replace in-duct filters more often during and after wildfire season. Heavy use can mean every 1 to 3 months.
- Fan readiness: Test continuous fan operation. Consider an ECM blower for efficient long run times.
- Ductwork: Inspect and seal seams and boots with mastic or foil HVAC tape.
- Keep spares: Store extra HEPA cartridges and MERV-13 filters before wildfire season.
Special considerations for vulnerable people
Prioritize bedrooms and main living areas for filtration if you have children, older adults, pregnant people, or anyone with heart or lung conditions in the home. Consult your clinician for personalized guidance and medications. If indoor PM2.5 cannot be kept within targets, focus on your clean room or consider temporarily relocating until outdoor air improves.
Masks for going outside
When you must go outdoors during smoky periods, a well-fitting N95 or KN95 respirator offers much better protection than cloth masks. For children, follow pediatric and local guidance on fit and availability. Indoors, masks are usually not needed when your air is kept within targets, though highly vulnerable people may still choose to wear an N95 if indoor levels are elevated.
Bringing it all together
A few smart choices go a long way in Tigard. A MERV-13 in your HVAC, properly sized HEPA units, basic air sealing, and steady monitoring can keep your indoor air far cleaner when smoke rolls in. With a pre-season plan and a well-prepared clean room, you can protect your household and maintain comfort throughout wildfire season.
If you are planning a move or preparing a property for market, indoor air readiness is a smart quality-of-life upgrade. For tailored guidance on presenting and protecting your Tigard home, request a concierge conversation with Unknown Company. Request a Luxury Consultation & Market Valuation.
FAQs
What PM2.5 level is safe for indoor air during wildfire smoke?
- Aim to keep indoor PM2.5 below 35 µg/m3 during smoke events, and ideally below 12 µg/m3 when possible.
How do I know if my HVAC can handle a MERV-13 filter?
- Have a qualified HVAC technician check static pressure and blower capacity; some systems need a thicker media filter or an ECM blower to maintain airflow.
How many HEPA units do I need for my home in Tigard?
- Size each unit by CADR for the room it serves; larger homes often need one for each bedroom and one for the main living area to reach 4 to 6 ACH.
Should I turn off my ERV or HRV during heavy smoke?
- Most manufacturers recommend turning off or reducing outdoor intake during heavy smoke to avoid bringing polluted air inside.
Are Corsi-Rosenthal boxes as effective as store-bought HEPA units?
- A properly built unit with MERV-13 filters can deliver CADR comparable to mid-range HEPA models, though noise can be higher and filters load quickly.
What should I do if indoor PM2.5 stays high even with filtration?
- Add more filtration, reduce air leaks, retreat to a clean room with 4 to 6 ACH, and consider temporary relocation for vulnerable individuals until outdoor air improves.
