Is it better to use fresh air system or photocatalyst in in addition to formaldehyde?

When ultraviolet light is used, photocatalyst will react with formaldehyde in indoor air. It can only temporarily remove formaldehyde from indoor air, so its useful but short-term effect will rebound after a period of time. Even imported brands have radiation to human body, which is not recommended.

The physical purification of fresh air system has good in addition to formaldehyde ability and can remove formaldehyde in a short time. Ordinary fresh air system can't be purified, so we have to choose a higher filtration level, such as the purification level reaching the European standard H 13 level (operating room level). For this piece, Thomas (USA) and Giaconya (Germany) are recommended to perform better.