I recently found this article by EWG, putting limonene-containing cleaners on the bad list of toxic household cleaners:
The claim is that limonene reacts with trace levels of indoor ozone to produce formaldehyde. Yet, citrus oils can be around 90% limonene or d-limonene. Does this mean that everything citrus or pine is dangerous now? Including orange essential oils, orange juice, orange scented diffusers and room sprays, candles with citrus oils, etc?