English: This video shows that due to the possible significant leakage of unfiltered air through the gaps between the mask and the face a summary protective efficacy of a negative-pressure half-mask respirators masks are extremely low. Unfortunately, sellers RPD in RF and other post-Soviet countries use the incompetence of the consumer and the lack of adequate legislation, and exaggerating the efficacy of their products by orders of magnitude. The usage of certainly not enough effective types of respirators (part of which was designed more than half a century ago) leads to the development of occupational diseases, including irreversible and incurable pneumoconiosis (silicosis, anthracosis, etc) and chronic obstructive pulmonary disease, and many others.