Submicronic fungal bioaerosols: high-resolution microscopic characterization and quantification.

Submicronic particles released from fungal cultures have been suggested to be additional sources of personal exposure in mold-contaminated buildings. In vitro generation of these particles has been studied with particle counters, eventually supplemented by autofluorescence, that recognize fragments by size and discriminate biotic from abiotic particles. However, the fungal origin of submicronic particles remains unclear. In this study, submicronic fungal particles derived from Aspergillus fumigatus, A. versicolor, and Penicillium chrysogenum cultures grown on agar and gypsum board were aerosolized and enumerated using field emission scanning electron microscopy (FESEM). A novel bioaerosol generator and a fungal spores source strength tester were compared at 12 and 20 liters min(-1) airflow. The overall median numbers of aerosolized submicronic particles were 2 × 10(5) cm(-2), 2.6 × 10(3) cm(-2), and 0.9 × 10(3) cm(-2) for A. fumigatus, A. versicolor, and P. chrysogenum, respectively. A. fumigatus released significantly (P < 0.001) more particles than A. versicolor and P. chrysogenum. The ratios of submicronic fragments to larger particles, regardless of media type, were 1:3, 5:1, and 1:2 for A. fumigatus, A. versicolor, and P. chrysogenum, respectively. Spore fragments identified by the presence of rodlets amounted to 13%, 2%, and 0% of the submicronic particles released from A. fumigatus, A. versicolor, and P. chrysogenum, respectively. Submicronic particles with and without rodlets were also aerosolized from cultures grown on cellophane-covered media, indirectly confirming their fungal origin. Both hyphae and conidia could fragment into submicronic particles and aerosolize in vitro. These findings further highlight the potential contribution of fungal fragments to personal fungal exposure.

Visualisation and identification of peak exposure events in aluminium smelter pot rooms using hydrogen fluoride and aerosol real-time portable spectrometers.

A recently developed novel portable real-time hydrogen fluoride spectrometer was used with an aerosol PM10 spectrometer under a PIMEX telemetric measurement strategy to visualize and identify simultaneous occupational air peak exposure events to hydrogen fluoride and PM10 aerosol sub-fractions in aluminium smelter pot rooms using Søderberg or Prebake anode technologies. The hydrogen fluoride and the aerosol concentration data measured during different work operations are plotted and evaluated applying the synchronised videos and air concentrations measured by the spectrometers. The main point-emission sources of HF and PM10 were identified and assessed. The major finding in the study was that the main source of PM10 and HF was partly open cells in a Søderberg pot room, whereas in a Prebake pot room, the point emissions of the two contaminants were associated with hot bath residues and hot replaced anodes. In order to prevent the simultaneous exposure to HF and PM10 among pot room workers it is important to prevent workers from being close to these point-sources under unfavourable ventilation. Storage of hot residues outside electrolytic cells without any point source ventilation should not occur.

Compact semi-automatic incident sampler for personal monitoring of volatile organic compounds in occupational air.

Suddenly occurring and time limited chemical exposures caused by unintended incidents might pose a threat to many workers at various work sites. Monitoring of exposure during such occasional incidents is challenging. In this study a compact, low-weight and personal semi-automatic pumped unit for sampling of organic vapor phase compounds from occupational air during sporadic and suddenly occurring incidents has been developed, providing simple activation by the worker potentially subjected to the sudden occurring exposures when a trained occupational hygienist is not available. The sampler encompasses a tube (glass or stainless steel) containing an adsorbent material in combination with a small membrane pump, where the adsorbent is capped at both ends by gas tight solenoid valves. The sampler is operated by a conventional 9 V battery which tolerates long storage time (at least one year), and is activated by pulling a pin followed by automatic operation and subsequent closing of valves, prior to shipping to a laboratory. The adjustable sampling air flow rate and the sampling time are pre-programmed with a standard setting of 200 mL min(-1) and 30 min, respectively. The average airflow in the time interval 25-30 min compared to average airflow in the interval 2-7 min was 92-95% (n = 6), while the flow rate between-assay precisions (RSD) for six different samplers on three days each were in the range 0.5-3.7%. Incident sampler recoveries of VOCs from a generated VOC atmosphere relative to a validated standard method were between 95 and 102% (+/-4-5%). The valves that seal the sampler adsorbent during storage have been shown to prevent an external VOC atmosphere (500 mg m(-3)) to enter the adsorbent tube, in addition to that the sampler adsorbent is storable for at least one month due to absence of ingress of contaminants from internal parts. The sampler was also suitable for trapping of semi-volatile organophosphates.