Page references in bold indicate tables and references in italics indicate figures. accumulation mode 8 ACGIH inhalable fraction and 250 occupational exposure limits 294 particle size-selective aerosol sampling criteria 271 respirable fraction curve 271, 272 thoracic fraction curve 271, 272 TWA TLVs for selected substances occurring in workplaces as aerosols 295-296 aerobiology 473 aeroconiscope 477 aerodynamic diameter 4, 27-28, 268 aerodynamic particle sizer (APS) 61, 64, 66, 67, 501, 502 Aerojet-General glass cyclone sampler 485 aerosizer 501 aerosol concentrations 11, 228, 313, 320, 489, 490 aerosol exposure 222-227, 291 definitions of 225-226 history 226, 231 human respiratory tract 223-225 indices of 313, 320-322 inhalation 223 occupational exposure limits 294-297 sampling frequency 231 typical cumulative 230, 231 variability of 227 aerosol fractions, identification of 270 aerosol mass concentration 9 aerosol materials 57-59 aerosol measurement 8-9 aerosol mechanics 22-33 drag coefficient 22-23 general equation of motion under the influence of an external force 24-25 impaction 28-30 molecular diffusion 30-32 particle aerodynamic diameter 27-28 particle drag force and mobility 22 particle motion without external forces 25-26, 27 slip 23-24 turbulent diffusion 32-33 aerosol particle size distribution see particle size distribution aerosol particle size selection after aspiration see particle size selection after aspiration aerosol sampler studies, experimental methods 35-70 assessment of collected aerosol 60-61 direct (trajectory) method 35-36, 37, 101 indirect (comparison) method 36-37, 60, 102 methodology for assessing sampler performance 35-38 protocols and procedures 61-68 reference methods 60 test aerosol generation 50-60 test facilities 39-50 aerosol samplers air and particle movement near single-entry 9, 10 in the ambient atmosphere, field experience with 575-598 line and point sink samplers 71-72 nature of air flow near 71-91 performance characteristics 9-12 rebound of particles from outer walls of 170 for the respirable fraction 359-385 scaling relationships 38-39 thick-walled tubes 75-76 thin-walled slot and tube entries 73-75 aerosol samplers in the workplace 537-573 converting particle counts to particle mass 549-558 diesel particulate matter 568-569 future of workplace aerosol measurement 569-570 personal and static (or area) sampling 538-539 relationship between 'total' and inhalable aerosol 539-549 for respirable aerosol fraction 558-