ABSTRACT
<p><b>OBJECTIVE</b>To evaluate the protective performance of a positive pressure bio-protective clothing against viral aerosol.</p><p><b>METHODS</b>The suspension of indicating virus phage Phi-X174 was made for viral aerosol generating in a hermetic cabin. The diameter of viral aerosol particles were measured with a aerodynamics size analyzer. By adjusting the inner humidity of the cabin, the protective efficiency of the positive pressure bio-protective clothing against viral aerosol in high and low windshield conditions was determined with Andersen six-stage air sampler sampling and plage forming unit (PFU) counting, respectively.</p><p><b>RESULTS</b>The mass median diameter of Phage Phi-X174 aerosol particles was about 0.922 µm and the background concentration is beyond 2 × 10⁴ particles/m³. The protective efficiency of the clothing against phage Phi-X174 aerosol particles was above 99.9% under different test conditions with the range of viral aerosol concentration between 0 - 23 PFU/m³. Airflow (P = 0.84), environment humidity conditions (P = 0.33) and sampling time (P = 0.07) did not affect the protective efficiency statistically.</p><p><b>CONCLUSION</b>The positive pressure bio-protective clothing provided a relatively high efficiency against phage Phi-X174 aerosol regardless of airflow rate, environment humidity and sampling time.</p>
Subject(s)
Aerosols , Bacteriophage phi X 174 , Bioterrorism , Equipment Design , Humidity , Occupational Exposure , Pressure , Protective Clothing , Time Factors , Virus DiseasesABSTRACT
Objective To investigate the endurance or resistance of different bacteriophages to bubbling stress in different sampling solutions,to select the optimum sampling solution from three different ones and to select relatively stress-resistant bacteriophages from five different ones.Methods AGI-10(all glass impinger)was used as the representative for all the impingers that would bubble during operation to fulfill the bubbling experiment.Three different sampling solutions used,such as distilled water(DW),phosphatic buffer solution(PBS),and suspension medium(SM),were divided into two groups by adding olive oil(50 μl) or otherwise(0 μl).The impingers were operated 30 min at a flow rate of 7.0 L/min.The titers of bacteriophages and the volume of final sampling solutions were determined before the corrected survival probability was used to evaluate the stress resistance of several different bacteriophages.Results It was found that the survival probability of the same bacteriophage bubbling with different sampling solutions was different except for bacteriophage F2.The use of SM as the collection fluid was related to a high survival probability which remained unchanged between 50 μl and 0 μl olive oil.The corrected survival probability was 79%,77%,86%,50% and 71% for phage SM701,SM702,PhiX174,EcP1 and F2 respectively after 60 minutes of impingement at a flow rate of 7.0 L/min.Conclusion The endurance or resistance of different kinds of bacteriophages in the same sampling solution is different.SM might be an optimum sampling solution for phages.Bacteriophage SM701,SM702 and PhiX174 are more resistant to bubbling stress than EcP1 and F2.
ABSTRACT
<p><b>OBJECTIVE</b>To establish a testing and evaluating method for filtration efficiency of the canister against microbial aerosol.</p><p><b>METHODS</b>Serratia marcescens aerosol served as model of bacterial aerosol, Bacillus subtilis var niger aerosol as model of spores aerosol, bacteriophage f(2) aerosol as model of viral aerosol. Employing the microbial aerosol testing platform was established in lab, models of microbial aerosol generated artificially were sampled quantitatively by air samplers before and after filtrating by canisters, respectively. Filtration efficiency was determined by the concentration of microbial aerosol in the air sample before and after filtrating. The four canisters of 1-1, 1-2, 1-3, 1-4 were tested for the filtration efficiency against Serratia marcescens, Bacillus subtilis var niger and phage f(2) aerosol. The two canisters of 543 and 544 canisters equipped with active carbon were tested for the filtration efficiencies against Serratia marcescens aerosol.</p><p><b>RESULTS</b>The filtration efficiency of 1-1, 1-2, 1-3 canisters against Serratia marcescens, Bacillus subtilis var niger and phage f(2) aerosol was 100.000%. The filtration efficiency of 1-4 canister filtration efficiency against Bacillus subtilis var niger spores aerosol was 99.997% and efficiency of the other two aerosol was 100.000%. The filtration efficiency of the two canisters of 543 and 544 to those attached with active carbon against Serratia marcescens aerosol was 100.000%.</p><p><b>CONCLUSION</b>The testing method might be used to evaluate the protective performance of the canister against microbiological aerosol. The effect of the canisters (including those equipped with active carbon) against microbiological aerosol should be reliable.</p>