EPA Study — DIY Air Cleaners Reduce Wildfire Smoke Indoors

Source: U.S. EPA Research “Research on DIY Air Cleaners to Reduce Wildfire Smoke” US EPA

Summary

The U.S. Environmental Protection Agency carried out research to evaluate how DIY air cleaners (homemade units) perform in filtering out smoke particles from wildfire smoke indoors. The study used simulated wildfire smoke (from smoldering pine needles) in a controlled chamber and compared different designs of DIY air cleaners, including various filter ratings and fan setups. US EPA

Findings:

• DIY designs using MERV-13 filters attached to box fans (or similar) significantly reduce smoke particle concentrations. More elaborate designs (multiple filters, better sealing, add-on shrouds) improve effectiveness. US EPA

• Clean Air Delivery Rate (CADR) measurement shows that some DIY designs can approach or even outperform lower-end commercial units in terms of particle removal per cost. US EPA

• Safety was tested: newer model box fans (since ~2012) with proper safety features (fused plugs, etc.) did not show excessive heating or fire risk even when filters loaded with smoke/dust; however, caution is needed with older or lower-quality components. US EPA

• The condition of filters matters: dirty filters significantly reduce performance, emphasizing need for regular replacement. US EPA

Understanding and Analysis

This study is very important, especially as wildfire smoke events are increasing globally due to climate change. Key takeaways and implications:

1. Cost vs Performance Trade-off: Commercial air purifiers with high CADR and HEPA/VOC filters are effective but can be expensive. DIY units, when well designed, offer a very cost-effective alternative. For communities or households with budget constraints, this can meaningfully improve indoor air during smoke events.

2. Design matters: A basic fan + filter setup works, but better configurations (multiple filters, better sealing, suitable fans) significantly improve outcomes. Poor sealing or undersized filters can reduce effectiveness greatly.

3. Maintenance is essential: Performance degrades as filters load up with smoke and particles. This echoes findings in many studies: air purifier units are only as good as their filter condition. Users must monitor and change filters to maintain safety and efficacy.

4. Safety considerations: Even though the tested setups did not pose fire or burn risk under tested conditions, DIY builds vary widely. It’s important to use reliable components, good wiring, and avoid obstructing airflow. Standards or guidelines help.

5. Real-world applicability: While lab chamber results are promising, real homes are different (leakage, ventilation, multiple pollutant sources, occupant behavior). But this work provides strong evidence that DIY options are not just theoretical—they have practical value.

Challenges & Further Research Needed

• Standardization: What filters, fans, and configurations give safe, high CADR at low cost? There is variation; more guidelines / product templates would help.

• Noise, airflow, power: DIY units might be loud or consume more power at high fan speed. Comfort and cost of electricity matter for adoption.

• Filter disposal and availability: Access to good filters (MERV-13 or better) regularly is necessary. In some regions, supply chain or cost could be a barrier.

• Integration with other mitigation strategies: Using DIY air cleaners is one approach. Proper ventilation (when outdoor air is clean), sealing gaps, reducing indoor sources of pollution (smoking, cooking, etc.) also matter.

Conclusion

The EPA study shows that DIY air cleaners are a valuable tool in improving indoor air quality during wildfire smoke events. For many households, they provide an affordable mitigation strategy. Moving forward, developing user-friendly design templates, safety guidelines, and awareness among the public will enhance their impact. In policy terms, supporting low-cost air cleaner adoption in vulnerable communities could reduce health burdens during smoke seasons.