Measurement of human exposure to biologically relevant fractions of inhaled aerosols.

Abstract

Aerosol sampling has evolved with changes in technology and our understanding of the importance of assessing the biologically relevant fractions of the total aerosol. During the past decade there has been international agreement on the definitions for the inhalable, thoracic, and respirable fractions and instruments have been developed to collect samples according to these conventions. These measurement techniques are now well established in the workplace and are increasingly being applied to assessments of nonoccupational exposure, as the practical diYculties in obtaining samples over 24 hours have been solved. It is argued that multiple aerosol size fractions should be measured for hazardous substancessuch as inorganic lead-in which inhaled material may either be absorbed in the alveoli (respirable) or cleared from the ciliated airways in the lung to the gut and then absorbed (thoracic and extrathoracic). Such measurements should improve the evaluation of the risk for inhaled lead, particularly for non-occupational exposure of children. Also, passive aerosol sampling techniques may enable measurements of non-occupational exposure to be made over several weeks and this would also help improve the reliability of the risk evaluation for aerosol toxicants with a long biological half life. However, further development of these techniques is required if they are to be practicable and biologically relevant. (Occup Environ Med 1999;56:747-752)

Particle Size Analysis in Aerosol-Generating Dental Procedures Using Laser Diffraction Technique

“…In considering the transmission of pathogens such as viruses in the respiratory tract, diameters of aerosols and droplets are the most critical factor [36,37]. Theoretically, the size of aerosol particles that can cause airborne infection is thought to be <5 µm, and interestingly the study at the Wuhan hospital showed that SARS-CoV-2 virus particles were mainly detected in aerosols in two peaks (0.25-1.0 and 2.5-5.0 µm), indicating that aerosols containing virus have bimodal characteristics [5].…”

Assessment of Lead Exposure Risk in Locksmiths

“…Adding lead to brass, typically about 2% lead, makes it easier to cut the keys [ 11 ]. Although the dose appears low, inhaled lead particles that penetrate to the unciliated airways (100% for particles less than <1μm and up to 50 % of particles that are <50μm) are completely absorbed; particles cleared from the ciliated airways and those settling in the area above the trachea are typically ingested with 10% to 15 % being absorbed in adults and up to 50% in children [ 5 , 26 , 27 ]. Even though most of the lead exposure among locksmiths may be “subclinical”, recent research has nonetheless indicated that chronic low level lead exposure to adults poses significant risks for hypertension, adverse reproductive outcome, and possibly renal dysfunction [ 21 – 23 , 28 , 29 ].…”

“…Among these are workers of brass foundry and brass product manufacturing industries. A major route of exposure to lead and other toxic substances in these workers is inhalation of fumes and dust particles [ 5 ]. Workers exposed to lead fumes and dust particles may inadvertently contaminate their homes and expose family members with lead dust particles transported on their clothes, skin, hair, tools and in their vehicles [ 6 , 7 ].…”

The impact of particle size selective sampling methods on occupational assessment of airborne beryllium particulates

“…Comprehensive and detailed histories of occupational particulate air sampling, especially particle-size selective methods, have been published by others. 3,4 Only a brief overview will therefore be provided here.…”