Why is the air in coniferous forests practically free of disease-causing bacteria?

The thing is that needles have properties to destroy many pathogens. Therefore, walks in the coniferous forest are very beneficial to health. In the past, people used to bring coniferous branches into their homes to protect themselves from disease. Of course, this had not a scientific, but a magical justification, as if the needles scare away evil spirits that cause diseases. But the study of conifers has confirmed that the substances secreted by these plants have antiseptic properties. A large number of medical preparations are made from them.