| With increased awareness of health and protection,personal protective equipment has become a necessity in the daily life of the general public.In particular,masks,which have the most direct contact with the human respiratory system and are most widely used,have become one of the hot topics of research in the field of environment and health in recent years.Masks are the most common measure to block the spread of respiratory pathogens and prevent respiratory infections.However,it is not clear whether particles,including chemical and biological components,can be released from the surface of the mask.The health risk of these particles being ingested by humans has also yet to be studiedTo answer these questions,this study designed a mask pollutant emission monitoring system,which can systematically obtain the release characteristics of solid and gaseous pollutants on the mask surface,and reveal the factors and action mechanisms affecting the release of different pollutant components.It mainly includes:(1)Dynamic characteristics of particle size and concentration of particles released from the surface of different types of masks are obtained in real time through online monitoring equipment;(2)Studying the microbial characteristics of the mask surface under different conditions by swab sampling and media culture,and revealing the characteristics of microbial community composition on the mask surface and facial skin surface by molecular biology techniques such as high-throughput sequencing;(3)Using ICP-OES to obtain the list of extractable heavy metal elements in masks;(4)Using thermal desorption and gas chromatography-mass spectrometry(GC-MS)to obtain the types and concentrations of key VOCs released from different masks;(5)The deposition flux and exposure risk of pollutants released from masks after being inhaled by humans are assessed based on the respiratory exposure model,and the potential exposure risk of different components are assessed based on the dermal exposure model.The research results indicate that there are a large number of solid pollutants that can be released from the surface of masks,and the concentration of shed particulate matter also shows a significant increase trend with the increase of mask wearing time.Among them,KN95 masks have higher shedding concentration than disposable medical masks in the small particle size segment(0.3-1.0μm),and the concentration of particles shed by the two types of masks is comparable in the particle size range larger than 1.0μm(59007 N/m3 and 58429 N/m3,respectively).For the same mask,the concentration of particulate matter shed on its middle surface is the highest,followed by the inner surface and finally the outer surface.After wearing,there are a large number of microorganisms on the surface of the mask,and their number significantly increases with the increase of storage time.The bacteria on the inner surface of the mask originate mainly in the skin of the face.Secondly,this study also found the presence of seven heavy metal elements in the masks,including zinc,nickel,copper,mercury,chromium,cadmium,and iron,with concentrations ranging from 0.02 to 3.20 mg/kg.In addition,various VOCs such as toluene,n-octane,and 3-methylhexane released from the mask can be detected in the air downstream of the mask,with release rate range of 0 to 1.0 μg·m-2·h-1.This study also found that after placing or wearing a mask for a period of time,the concentration of VOCs released from the mask will gradually decrease.The noncarcinogenic risk of the six heavy metal elements detected in this study is at an acceptable level.However,the carcinogenic risk of Cr in disposable medical masks exceeds 10-6,which need to raise people’s high alert.The release of VOCs during mask wearing does not pose significant health hazards,but the cumulative carcinogenic risk of VOCs in the new KN95 mask is close to the threshold,which should raise people’s awareness.The results of the study can provide a new scientific method and theoretical basis for the study of the environmental and health effects of exhaled bioaerosols,and provide an important reference for the development and implementation of personal protective measures,especially the optimal design,standardized use,and elimination and disposal of masks and other related mask standards. |
