Dust and Gases

Question 1

TWA

Answer 1

Time weighted average

• Defined as the TWA ariborn concentration of a particual substance when calculated over a normal 8-hr work day, 5 day working week

Question 2

STEL

Answer 2

Short Term Exposure Limit

• 15minute time weighted average exposure which should not be exceeded at any time during a work day

Question 3

Primary hazard associated with dust

Answer 3

• general term for group of diseases of the respiratory organs

Question 4

Dust sampling

Answer 4

• Gravimetric Samplin

- Laser Photometer

Question 5

Dust prevention

Answer 5

• Removal of personnel
  > during blasting
  > return airway access

-Prevention at source
> control at source
> water when drilling
> water stock piles
> water down roads 

• Dilution
  > Increase airflow
• Filtration
  > Bag filter
  > Cyclones
  > Wet scrubbers

Question 6

Explosive Dust

Answer 6

• Sulphide Dust
• Created during blasting of rock with high sulphide content
• Coal dust

Question 7

Toxic Gases

Answer 7

> Nitrous fumes
Sulphur Dioxide
Ammonia

Question 8

Carbon Dioxide

Answer 8

• colourless, odourless

- does not support combustion

Question 9

Carbon Monoxide

Answer 9

• mainly blasting and diesel engines
• Colourless, odourless
• headaches, dizziness,

Question 10

Nitrous Fumes

Answer 10

Irritation of eyes, chest, nose and throat

Question 11

Methane

Answer 11

Can cause headaches and dizziness