What does COMAH stand for?
Control of Major Accident Hazards Regulations 2015
What conditions must be met under COMAH for a permit to be issued by the HSE?
Evaluations of potential accidents and their impact on workers onsite and surrounding populations.
Why do “domino effects” also have to be considered under COMAH?
There could be domino effects on other establishments where substantial major accident hazards already exist and these must be evaluated (risk of compounding) as well as impact on neighbouring companies which must also be approached and informed.
Who must be informed about the major accidents of a company under COMAH?
It requires regular reporting to authorities to HSE and local population must be informed about the course of action to be taken if the major accident occured.
What are the powers of the HSE?
Powers to inspect, investigate and prohibit operation.
What must be included in the written major accident prevention policy?
- ensuring a high level of protection for human health and the environment
- be proportionate to major accidents
- set out operators overall aims and principles of action
- set out the roles and responsibility of management and its commitment towards continuously improving control of major accident hazards.
To what is COMAH regulations applicable to other than individual substances?
- Health Hazards (acute toxicity, specific target organ toxicity)
- Physical Hazards (flammable, explosive, oxidising)
- Environmental Hazards (acute or chronic toxicity to acquatic life)
What will COMAH always specify for the regulations to apply to the substance?
A minimum inventory
What two types of numbers are given under COMAH?
- a lower one for which ‘Lower Tiers’, less stringent rules apply
- a higher one for which ‘Higher Tiers’, tougher requirements apply
In the case of multiple hazards for one substance, the more stringent limits apply
What happens if several substances or several locations for one substance are present?
Regulations give rules for their combined effect
Give examples for the differentiation of substances between ‘toxic’ and ‘very toxic’.
- IDLH (Immediate damage to life and health)
- minimum notifiable inventory - amount of material that must be stored before authorities notified
- TLVs and estimates of lethal concentration
What is the overriding concern in COMAH? (Similar to concentration in normal operation which is the overriding concerning for Air Quality Standards)
The toxic load to which people may be exposed during an accident. This approach factors in the duration of exposure of people to the pollutant.
What are the stages in estimating the accidental release of pollutant?
- Model gas dispersion to predict concentrations at ground level with respect to position and time
- Use time varying concentrations to estimate toxic-load (dosage) D* to which someone would be exposed while remaining there
- Compare to EITHER SLODS and SLOTS value for the substance OR expected % fatality from Probit correlation using D*
What is the equation for the lethal time?
The lethal time for a conventionally toxic material (not radioactive or carcinogenic) varies inversely with concentration raised to power n.
t = (LDp)/c^n
where LDp is the level of toxicity killing p% people
c is the concentration
t is the duration of exposure to c after which level of toxicity corresponding to LDp is experienced
Which is worse breathing in a given amount of material at high concentration for a short time or breathing in at lower concentration for a proportionately long time?
Breathing in a given amount of material at a high concentration for a short period of time. This is because for typical substance n is greater than 1.
What is the equation for the dosage?
The dosage is the intergral of the concentration raised to power n over time from 0 to infinity.
What does DTL stand for?
Dangerous Toxic Load
What is the DTL?
It is the exposure conditions in terms of air-borne concentration and duration of exposure which would produce a particular level of toxicity in the general population.
What are the two main levels of toxicity?
- SLOT
- SLOD
To what do both SLOD and SLOT refer?
They refer to the definition of the dosage LDp at a probability of death p.
What does SLOT stand for?
Specified Level of Toxicity
What probability of death p does SLOT refer to?
p = 1 % (LD 1)
What probability of death p does SLOD refer to?
p = 50 % (LD 50)
Describe the effects on the general population if the SLOT is attained
- Specified stress to almost everyone in the area
- Substantial fraction of people require medical attention
- Some people seriously injured, require prolonged treatment
- Highly susceptible people possibly killed
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Global Issues Part 142
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Global Issues Part 243
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Environmental Legislation30
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Environmental Standards12
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Acid Gases42
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Atmospheric Dispersion of Pollutants - Part 143
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Atmospheric Dispersion of Pollutants - Part 234
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Atmospheric Dispersion Models - Solving the Mass Balance10
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Modelling Atmospheric Dispersion12
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Modelling Dense Gases15
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COMAH Regulations41
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Water Pollution52
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Water Regulations12
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Waste BATs for Water34
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Aerobic Digestion52
