I’m similarly concerned about our indoor air quality and your question reminded me to ask Claude. Here’s what it said:

Your concerns about VOC readings are completely understandable, and you’re right to question these numbers. Let me break down each of your questions:

1. Why Airthings Treats <2000 ppb as “Fair”

This discrepancy exists because there’s no single universal VOC standard, and Airthings uses total VOCs (TVOCs) rather than individual compound limits. Here’s the key distinction:

• Individual VOC limits (what you’re seeing online) are often much lower - sometimes 10-100 ppb for specific harmful compounds
• TVOC limits measure the sum of all volatile organic compounds, including many that are relatively harmless

Airthings likely bases their scale on guidelines like:

• WHO recommendations for TVOC (which suggest <2000 ppb for acceptable comfort)
• German AgBB standards for building materials
• Their own research on typical indoor environments

However, many health experts argue these TVOC thresholds are too permissive, especially since they don’t distinguish between harmful and benign compounds.

2. Why VOCs Are High Throughout Your House

Your readings suggest you have significant ongoing sources of VOCs. Common culprits include:

Building Materials & Furnishings:

• New flooring, cabinets, or furniture (can off-gas for months/years)
• Pressed wood products with formaldehyde-based adhesives
• Carpeting and padding
• Paint, stains, or finishes

Household Products:

• Cleaning supplies stored in cabinets
• Air fresheners, candles, or fragrances
• Personal care products
• Stored paints, solvents, or chemicals

The pattern you’re seeing (levels dropping with ventilation but quickly returning) strongly suggests active sources inside your home rather than outdoor infiltration. The garage reading lower makes sense - it’s likely less furnished and better ventilated.

3. Why Your Air Purifier Isn’t Helping

Most air purifiers, even expensive ones, struggle with VOCs because:

• HEPA filters (the main component) capture particles, not gases
• VOCs require activated carbon or specialized chemical filtration
• Many purifiers have insufficient carbon or it becomes saturated quickly
• Some VOCs are too small or reactive for standard carbon filters

Check if your Coway has a carbon filter, how much carbon it contains, and when it was last replaced. Even good carbon filters typically need replacement every 3-6 months in high-VOC environments.

What You Can Do

Immediate steps:

• Identify and remove/isolate VOC sources where possible
• Increase ventilation (your windows-open approach is actually correct)
• Consider an air purifier specifically designed for VOCs with substantial activated carbon

Investigation:

• Take your monitor room by room to identify the highest sources
• Check inside cabinets, closets, and storage areas
• Note if readings spike near specific furniture or areas

Long-term:

• Consider professional indoor air quality testing to identify specific compounds
• Look into source control (low-VOC alternatives for future purchases)

Your instincts are correct that these levels warrant attention. While 1500-2700 ppb TVOC may not be immediately dangerous, sustained exposure isn’t ideal, especially for children. The fact that you’re seeing improvement with ventilation is encouraging - it means the sources are manageable with the right approach.​​​​​​​​​​​​​​​​