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Welding Fume Measurement from Hot Tap Welds at the National Hyperbaric Centre. John AS Ross Environmental and Occupational Medicine. Collaborators. University of Aberdeen, Dr Sean Semple – Enviromental & Occupational Medicine Prof Jonn Ayres

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welding fume measurement from hot tap welds at the national hyperbaric centre

Welding Fume Measurementfrom Hot Tap Welds at theNational Hyperbaric Centre

John AS Ross

Environmental and Occupational Medicine

collaborators
Collaborators
  • University of Aberdeen,
    • Dr Sean Semple – Enviromental & Occupational Medicine
    • Prof Jonn Ayres
    • Dr Andrea Raab – Trace Metal Speciation Laboratory
    • Prof Joerg Feldmann
  • University of Edinburgh
    • Dr Rodger Duffin Centre for Inflammation Research
    • Prof Ken Donaldson
  • University of London, King’s College
    • Prof Frank Kelly – Lung Biology Unit
  • Funding
    • University of Aberdeen
    • Acergy
    • Technip
why are we interested in welders
Why are we interested in welders?
  • Ischaemic heart disease
  • Pneumonia and death from pneumonia
  • A model of human particle exposure responses
    • – air pollution
  • We can measure higher levels of fume from hyperbaric chambers – dilution effect
  • ELTHI study cognitive symptoms
    • 6% Non-divers, 15% Divers, 28% Diver welders
  • Follow up study
    • 10% Welders, 33% Diver welders with symptoms
    • But welders exposed to 3 times more welding fume
    • And no dose response relationship between fume exposure and symptoms
    • However fume exposure higher in both welders and welder-divers with symptoms
definitions
Definitions
  • PM10 - mass of particles < 10 m diameter
  • PM5 - mass of particles < 5 m diameter
  • PM2.5 - mass of particles < 2.5 m diameter
  • PM1 - mass of particles < 1 m diameter
  • Nanoparticles - <100 nm diameter
slide7

Particle number count when shopping

walking on Union Street

eating area shopping mall

shop

shop

slide12

Metal Analysis

Most of the dust is insoluble in nitric acid/hydrogen peroxide and of whitish/grey colour. Did not contain crystalline quartz

slide16

Dust Trak

PM10

PM2.5

PM1

Mass/volume

Grimm

230->20,000 nm Particles/volume

P-Trak

<100 nm

Particles/volume

MSP WPS

10-200 nm Particles/volume

slide20

Dust-Trak and P-Trak

Particle Mass

Particle number

final comments on fume levels 1
Final comments on fume levels - 1
  • PM2.5 levels of less than 4mg m-3 are possible
  • P-trak levels of <2X106 cc-1 are possible
  • The work chamber ventilation system did reduce fume levels
  • Generation of nano-particles of a size not completely measured by P-Trak, Grimm or Dustrak identified
  • No evidence of agglomeration in atmosphere during welding
  • Filter respirators used in welding
    • Tested at 500 nm particle diameter
    • Edge leakage
  • Filters used in internal ventilation
    • May not be 100% effective until partially blocked by agglomeration
final comments on fume levels 125
Final comments on fume levels - 1
  • Welding fume can cause oxidant stress
  • Welding fume can cause inflammation in lung tissue
  • Nano-particles can probably enter blood via lung
  • Dermal uptake of nano-particle dust has been observed
  • Safe levels of nano-particle welding fume unknown
  • Area will expand as monitoring technology improves
toxicity
Toxicity
  • Conventionally related to mass of agent absorbed
  • Recently surface chemistry has also been identified as relevant
  • Surface area larger in smaller particle sizes
  • Smaller particles regarded as more active locally in triggering inflammation
  • Evidence mostly confined to vehicle/diesel engine exhaust
  • Titanium dioxide
methods
Methods
  • Measurement of fume during hot tap welding at pressure
  • Gas sampled via a quarter turn valve decompressing chamber gas into an open ended pipe reservoir
  • Free flow of about 30 l-1
  • Analysers sampling out of the reservoir
slide31

Number

17 April 2007

10-200 nm diameter particles

WPS 1000XP

Weighted for number, mass and surface area

Single epoch during welding

Surface Area

Mass

slide32

Number

17 April 2007

10-200 nm diameter particles

WPS 1000XP

Weighted for number, mass and surface area

Mean of 110 readings

Surface Area

Mass

work in progress
Work in Progress
  • Detailed metal analysis from 4 welds
    • Trace Element Speciation Laboratory at the University of Aberdeen
  • Analysis of the oxidising power of welding fume in the lung in dust from four welds
    • Lung Biology Unit, King’s College, London University
  • Potential lung toxicity and inflammation potential in dust from four welds
    • ELEGI Colt Laboratory, the University of Edinburgh
  • The effects of 2mg m-3 welding fume inhalation in man
    • Environmental and Occupational Medicine, University of Aberdeen