Understanding Helio Air readings

The Helio Air reports five readings every 60 seconds. The app colours each one green, amber or red using the thresholds below.

PM2.5 (fine particles), µg/m³

• 0–12 green — clean air.
• 13–35 amber — moderate. Common while cooking, burning candles, or on wildfire-smoke days.
• 36+ red — poor. Run an air purifier or the HVAC fan, and avoid opening windows if outdoor air is the source.

CO₂, ppm

• 400–800 green — well ventilated.
• 801–1,200 amber — stuffy. People often report drowsiness above 1,000 ppm.
• 1,201+ red — ventilate. Open a window or run fresh-air intake.

VOC index, 0–500

VOC (volatile organic compounds) is an index, not a concentration. 100 is your home's typical baseline; values rise with cleaning products, new furniture, paint and cooking.

• 0–150 green
• 151–250 amber
• 251+ red

Temperature and humidity

Helio marks humidity outside 30–60 % as amber. Sustained humidity above 60 % increases mould risk; below 30 % is associated with dry skin and static.

Why readings look different from another sensor

Consumer sensors use different optical and electrochemical parts, so absolute numbers vary by 10–20 % between brands. Trends within one device are reliable; comparing two brands side by side is not.

Alerts

Turn alerts on in Devices → Helio Air → Alerts. You can set a quiet period (default 22:00–07:00) so amber alerts do not wake you; red alerts are always sent.