Efficacy of Structural Pasteuriza3on for Reduc3on of Viable Bacterial Levels in Indoor Environments Sean P. Abbo@, Ph.D. Natural Link Mold Lab, Inc., Reno, Nevada Larry Chase Precision Environmental, Ventura, California M. Chance Villines Natural Link Mold Lab, Inc., Reno, Nevada AbboB et al. Indoor Air 2011 Structural Pasteuriza3on Defini3on: An engineered process in which high temperatures are introduced into a structure or porIon of a structure for the purpose of reducing microorganisms to acceptable levels without damage to the structure AbboB et al. Indoor Air 2011 Pasteuriza3on Prior Research: •  Louis Pasteur 1854-­‐1864 •  PasteurizaIon of liquids and food •  PasteurizaIon of soils L. Pasteur, 1862
•  Wastewater management •  Heat treatment of wood in lumber industry Thermal Death Point: •  FuncIon of temperature and duraIon coupled with biomass and environmental factors AbboB et al. Indoor Air 2011 Efficacy Parameters Bacteria tested: 4 species Escherichia coli Klebsiella pneumoniae Pseudomonas aeruginosa Staphylococcus aureus Laboratory and Field data High Temperature/Short Dura3on vs. Low Temperature/Long Dura3on AbboB et al. Indoor Air 2011 Efficacy: Laboratory Studies Methods: •  Bacterial suspension applied to swab, in open glass test tube •  Test samples: placed inside dry convecIve heat chamber •  Range of temperature (45-­‐75°C) •  Range of duraIon (15 min – 5 d) •  Monitor for point at which complete mortality of sample reached •  Controls: before and a\er heaIng AbboB et al. Indoor Air 2011 High Temperature/Short Dura3on (HTSD) Complete mortality at 60-­‐75°C (140-­‐167 °F) for 0.25-­‐4 hr Escherichia coli
60°C 75°C
1.75 hr
<0.25 hr
Klebsiella pneumoniae
60°C
1.5 hr
Pseudomonas aeruginosa
60°C
1.25 hr
Staphylococcus aureus
60°C
4 hr
AbboB et al. Indoor Air 2011 Bacterial ReducIons Quantitative Reduction of viable E. coli Exposed to HTSD
1.0E+09
1.0E+08
1.0E+07
Viable Cells (CFU)
1.0E+06
1.0E+05
60ºC
65ºC
1.0E+04
1.0E+03
1.0E+02
1.0E+01
1.0E+00
Control
15
30
45
Duration (minutes)
60
75
120
Low Temperature/Long Dura3on (LTLD) Complete mortality at 45-­‐50°C (113-­‐122°F) for 4-­‐120 hr Escherichia coli
45-50°C
24 – 48 hr
Klebsiella pneumoniae
45-50°C
48 – 72 hr
Pseudomonas aeruginosa 45-50°C
4 – 24 hr
Staphylococcus aureus
120 + hr
45-50°C
AbboB et al. Indoor Air 2011 Efficacy: Field Studies Methods: •  Lab prepared samples •  E. coli selected as representaIve bacteria •  Test samples: placed inside structure during heaIng process •  60-­‐65°C for 2-­‐4 hr •  Control: transported to site, unheated AbboB et al. Indoor Air 2011 Efficacy: Field Studies Survival of E. coli under field structural pasteurization conditions
Exposure DuraIon Time 0
(preheat only)
Time 1
(0.5-1 hr)
Time 2
(2-4 hr)
Control
(unheated)
# Test Replicates # Field Projects Tested Survival (%) 10
2 80 15
2 13.3 204
177 5.9 180
177 100 AbboB et al. Indoor Air 2011 Structural Pasteuriza3on Implica3ons: •  ConvecIve dry heat can be used to saniIze building materials in situ •  Typically used in conjuncIon with structural drying and tradiIonal microbial remediaIon •  Allows for saniIzaIon of enIre structures, porIons of structures, or contents •  provides hygiene benefits by reducing overall levels of microorganisms in indoor environments •  Reduce risk of bacterial disease transmission •  ‘Green’ process, no anImicrobial chemicals, no development of resistant bacterial strains AbboB et al. Indoor Air 2011 Conclusions •  Structural pasteurizaIon can be effecIve to reduce environmental bacteria associated with damp structures and sewage loss situaIons •  60-­‐65°C for 2-­‐4 hours effecIve AbboB et al. Indoor Air 2011 Thank You! CONTACT INFORMATION: Sean AbboB – [email protected] Larry Chase – [email protected] AbboB et al. Indoor Air 2011