Indoor Air Quality
What Is MERV Rating?
Definition
MERV (Minimum Efficiency Reporting Value) is a 1-16 scale rating how effectively an air filter captures particles of different sizes — higher MERV traps smaller particles (like wildfire smoke and fine dust) but also restricts airflow more, which matters for a system not designed to handle it.
Why it matters for your home
During Pacific Northwest wildfire smoke season, a MERV-13-capable filter setup does real, measurable work on indoor air quality — but jumping straight to a MERV rating higher than your system is built to handle can starve airflow and stress the blower.
What to do about it
Confirm your specific HVAC system can support MERV-13 before upgrading filters — not every blower and duct system is rated for it, and our wildfire smoke guide covers the full picture.
Related terms
This definition is pending licensed-trade technical review. It's sourced from our own published service and guide content, not invented — but hasn't yet been signed off by a licensed HVAC reviewer.
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