2320 & 2420 Flashcards
Where is most of the responsibility for TDG placed?
Employers and workers that :
- prepare dangerous goods for transport
- operate transport vehicles containing dangerous goods
- receive dangerous goods
- respond to emergencies involving dangerous goods
Who “owns” TDG law and enforcement?
Transport Canada, just like Health Canada “owns” WHMIS.
What are the classes of dangerous goods?
9 classes:
Class 1
Explosives, including explosives within the meaning of the Explosives Act
Class 2
Gases; compressed, deeply refrigerated, liquefied or dissolved under pressure
Class 3
Flammable and combustible liquids
Class 4
Flammable solids; substances liable to spontaneous combustion; substances that on contact with water emit flammable gases
Class 5
Oxidizing substances; organic peroxides
Class 6
Poisonous (toxic) and infectious substances
Class 7
Radioactive materials and radioactive prescribed substances within the meaning of the Atomic Energy Control Act
Class 8
Corrosives
Class 9
Miscellaneous products, substances or organisms considered by the Governor-in-Council to be dangerous to life, health, property or the environment when handled, offered for transport or transported and prescribed to be included in this class
What is a dangerous good according to the TDG Act?
Any product, substance or organism included by it’s nature or the regulation in any of the 9 classes in the TDG Act schedule.
Discuss safety marks and placards.
Safety marks must be on smaller dangerous goods containers under 450L.
Placards must be on bulk containers of dangerous goods over 450L.
Transport units (highway tanker) transporting dangerous goods must be placarded. - this alerts first responders. (not required on ships/aircraft)
Who requires TDG training?
Every person engaged in the handling, offering transport, or transporting dangerous goods.
Handling includes packing and receiving goods.
What must accompany dangerous goods when transported?
Very specific documents and signs/placards as appropriate.
What is required for TDG documents?
Documents must be transported with dangerous goods and include the following 4 pieces of information.
- UN ID number
- Official shipping name
- Hazard class
- Packing Group (if applicable)
Employers can design own documents, and can be hand written so long as required information is clear and indelible.
What information SHOULD be included on TDG documents?
9 items:
- Date
- Shipper name
- Shipper address
- 24 emergency number (which may be CANUTEC)
- Quantity & unit of measure
- Number of packages
- Shipping name (the TDG name of the dangerous good)
- TDG class
- UN number
Where should TDG documents be stored during transit?
Somewhere clear/obvious, and easily/safely accessible to the driver.
Must be accessible in the event of an accident.
Discuss TDG Placards
Required on containers with over 450L.
Required on transport vehicles, on both ends and both sides.
Must be in TDG class colour, in a diamond, with contrasting background.
Must usually be 250mm per side, unless on small container when can be reduced to min’ 100mm.
Must be weather-proof, visible, and durable.
Must be on vehicle before loading and removed when empty.
What are UN specification codes?
United Nations standard packaging codes.
Packaging with these codes is based on standards published by the UN.
The code includes a lot of information about the packaging.
What are the three major groups assigned roles by TDG law?
Handlers
Offerors for transport
Carriers
List the characteristics of a hazardous Material
Chemical or biological agents
Prevalent in the workplace
Has a history of causing occupational disease
Tend to be recognized by most workers/public
Have received significant media coverage
Perceived risk often higher than actual risk
Often governed by prescriptive regulation
Subject to regulatory oversight
Often produce anxiety in the workplace
Exposure control strategies generally well developed
Transportation highly regulated
List & describe the four functions of a manager.
POLC (aka PLOC)
Plan work
Organize work
Lead the team in the work
Control the work
Briefly describe the roles of federal and provincial/territorial governments in regulating hazardous materials.
The Canadian Constitution assigns responsibility for regulating certain things to provincial/Territorial governments and certain other things to the federal government.
Provincial
Safety of workers exposed to HM
Disposal of HM within the province
Federal
Safety of workers exposed to HM in federally regulated workplaces
HM disposal outside of Canada
Transport of HM by road/rail/ship/aircraft (note, road transport is delegated to provincial ministry)
Describe an exposure control plan as required by Canadian OHS law.
(a) a statement of purpose and responsibilities;
(b) risk identification, assessment and control;
(c) education and training;
(d) written work procedures, when required;
(e) hygiene facilities and decontamination procedures, when required;
(f) health monitoring, when required;
(g) documentation, when required.
Define hazardous material
HM is not defined in any Canadian OHS law. Other sort-of-related terms like hazardous product, controlled product and designated substance are defined in OHS law but not HM.
Canadian OHS laws are filled with regulations related to prevention of adverse worker exposure to materials that are hazardous to their health.
List the elements of a WHMIS program.
Worker Education & Training
Supplier Labels
SDS
Describe the information elements of WHMIS as a results of completing a standard WHMIS education course.
Basic understanding of the WHMIS program in the workplace
How to recognize and use WHMIS information
Major hazards of products in the workplace
Rights and responsibilities of employers and workers
Required contents of labels and SDS sheets including how to understand pictograms and terms.
Compare and contrast WHMIS education and WHMIS training.
WHMIS education teaches workers about the WHMIS system and hazards. The focus is on the WHMIS system.
WHMIS training trains workers how to safely work with the hazardous materials and what to do in the event of a problem. Training is specific to the materials and work being done.
Define acute
Sudden onset, brief duration, or short exposure.
Define carcinogen
A hazardous material that may cause cancer.
Define “chemical name”
A scientific designation of a substance made according to a set of rules and internationally recognized.
Define chronic
Gradual/prolonged onset, long-term duration, or repeated exposures.
Define corrosive material
A material that is liable to destroy or damage another material by chemical action.
Define IDLH
Immediately Dangerous to Life or Health
Used related for respirator selection.
The airborne concentration that poses a threat of death or permanent adverse health effects upon exposure.
Workers must have means of escape from environment in case of respirator failure.
When levels greater than IDLH, highly reliable breathing apparatus required.
Define skin irritatants
A material that may cause an allergic skin reaction after contact with skin.
Define skin irritatant
A hazardous product that may cause reversible damage to the skin such as redness, itching, or swelling.
What are the four WHMIS test questions?
What are the hazards of the product?
How are you protected from those hazards?
What do you do in case of an emergency?
Where can you get further hazard information?
What important information can be found on an SDS sheet?
Material hazards.
Recommended controls (engineering, administrative, PPE).
First aid and spill response recommendations.
Additional: disposal information, contact information, manufacturer information.
List differences between WHMIS 1988 and WHMIS 2015.
Different symbols/pictograms
MSDS are now SDS with new standard format
There is a new classification system for controlled/hazardous products.
There is a new grouping system for hazards.
Name the most common forms of asbestos and types of asbestos-containing materials found in Canadian workplaces.
Chrysotile (most common) Amosite Crocidolite Tremolite Actinolite Anthophyllite
Floor tiles, ceilings, brake pads, insulation, ship building.
List diseases associated with overexposure to asbestos fibres.
Pneumoconiosis and cancer (mesothelioma, lung cancer, GI cancer).
Describe the methods most commonly used to manage asbestos-containing material in place.
Inventory of ACM
Decision on fate of ACM (manage or remove/abate)
Managing in place
Removal/abatement
What is asbestos?
Asbestos is a commercial term that includes six regulated asbestiform silicate minerals (silicon + oxygen).
What percentage of asbestos in a material does WorkSafeBC require for it to be designated as asbestos-containing?
1% per course (0.5% per OHS reg).
Recognized occupational causes of pneumoconiosis
Silicosis
Asbestosis
Other
What is required to inventory ACM?
Determine: What kinds of ACM are present Where? Quantity? Condition of the ACM.
When should asbestos be abated (removed)?
When ACM risk is high and easily accessible to workers or the public. Examples commonly include fire insulation because it was extremely friable.
When ACM has a moderate or high risk and enclosure or encapsulation is not feasible.
When the perceived risk of ACM is unacceptable and abatement will address worker or public concerns.
What is white asbestos?
Serpentine minerals - Chrysotile are known as white asbestos.
It is the most commonly used asbestos (~90% of world use).
Wavey/curly fibers.
What is amphibole asbestos?
The other 5 asbestos fibers
Amosite, crocidolite, tremolite, actinolite, anthophyllite.
Straight, rod-like fibers.
What are the three most common types of asbestos?
Chrysotile (white asbestos)
Amosite (brown/grey asbestos)
Crocidolite (blue asbestos)
How is testing performed to test for asbestos?
Bulk sampling.
- Safe collection technique/sealing
- Sent to lab (1-10g)
- polarized microscopy
How is asbestos classified in Canadian OHS law?
Form of ACM Type of asbestos fibers Percentage of asbestos in material Friability of ACM Amount and location of the ACM
This all determines whether it is low/medium/high risk.
List five sources of inorganic lead and work activities where exposure may occur.
Lead-acid batteries, automotive repair
Lead solder - Jewlers or electricians soldering
Lead containing ore - foundry/refinery workers
Firearm ammunition - Police, shooting ranges
Lead paint, panels, tiles, piping - Demolition/renovation/lead abatement workers
Explain how lead dust and fume enters a workers’ body.
Inhalation and ingestion.
Breathing dust or fumes
Lead contaminated food/drink
Nail biting with lead on hands and other habits of putting objects in mouth
Organic lead can be absorbed through the skin (some pesticides)
Describe the health effects of acute and chronic exposure to inorganic lead.
The health effects from lead are the same regardless of the source or route of exposure.
Early lead toxicity symptoms are non-specific and can be difficult to recognize.
Acute toxicity can cause lethargy, headache, hyporexia, metallic taste.
Chronic toxicity can cause abdominal pain, constipation, muscle/joint pain, memory problems.
Lead toxicity can cause neuropathy, GI Dz, renal Dz, reproductive Dz. Also carcinogenic.
List and describe the elements of a lead exposure assessment.
1, Identification of sources of inorganic lead in the workplace.
2, Observation of work activities to determine which practices expose workers to lead inhalation or ingestion.
3, Hierarchy of controls. Where exposure cannot be eliminated, air monitoring and surface sampling necessary to determine exposure levels.
4, Health monitoring, often including blood sampling, should be implemented where practicable.
What is organic lead? what is inorganic lead?
inorganic or elemental lead is just lead. Organic lead is a combination of lead and carbon.
List 5 common products manufactured using lead.
Lead-acid batteries
Lead-paint on roads
Lead-containing weapons/ammunition
Decorative glass
Protective coating on underwater cables
Differentiate fumes vs vapours.
Vapours are gaseous. Solids heated turn to liquid and then gas. A gas rising from a heated liquid is a vapour.
Fumes are small solid particles suspected in the air. Smoke is a fume.
When lead is heated, it melts, some lead may be vapourized and turn into a gas. In the air, the lead vapour cools and forms particles in the air - now a fume.
Removal of which two hazardous materials does WorkSafeBC require 48 hours notice in advance?
Asbestos and lead.
List two physical forms of lead that can enter a worker’s body.
Fine dust and fumes.
List 5 similarities between asbestos and lead OHS regulations
- Exposure control plan requirements
- Air monitoring requirements
- Highly prescriptive methods of removal
- Removal risk classification levels
- Notice of project requirements
List 5 legal methods for the removal of lead-based paint/coatings.
Chemical strippers Manual scraping Heat guns Water jet blasting Dry ice blasting Specific dry abrasive blasting Wet abrasive blasting
What is a toxic process gas?
A gas that meets criteria in Canadian federal HPR (Hazardous Product Regulation).
Category 1, 2, or 3 for acute toxicity and is used in one of the following:
1, Part of an industrial process
2, Refrigeration
3, Material treatments (such as disinfection systems)
Specifically:
Anhydrous ammonia, chlorine gas, and sulfur dioxide.
What is Process Safety Management?
Important:
“PSM is an analytical tool used to prevent the release of substances defined as highly hazardous chemicals”
It is the formal process of assessing and controlling OHS issues created by process lines.
(Developed by OSHA)
Typical examples would include large scale industrial processes where each individual component has a direct impact upon the other components. This can lead to hazards when there is a change to any 1 component of the overall process.
What elements make up a typical process safety management plan?
Name at least 6.
Process Safety Information Process Hazard Analysis Operating Procedures Training Contractors Mechanical Integrity Hot Work Management of Change Incident Investigation Compliance Audits Pre-startup safety review Emergency planning and response Trade secrets Employee participation
What are common uses of ammonia in the workplace?
Refrigeration
Fertilizer
Component in industrial production.
What are the effects of overexposure to ammonia?
Irritation of nose and throat.
Coughing, shortness of breath, tightness of chest.
Burns to the eyes, nose, throat (anywhere with moisture).
Pulmonary edema.
What is the federal HPR?
Hazardous Product Regulation
Federal legislation that is related to WHMIS and toxic process gas. This regulation is referenced for definitions in BC OHS Regulation.
What is a process flow diagram?
A display of the relationship between major equipment/processes.
A simple diagram that depicts processes and how they are related in a larger design. It does not provide details of how each process functions or specifically how different components are connected (rather it shows that they are and in what direction).
Commonly used in chemical and process engineering.
What is a piping and instrumentation diagram/drawing?
A P&ID is a diagram that shows specifically how different components in an industrial process are connected and controlled.
There are standards symbols for these schematics.
What is anhydrous ammonia?
NH3.
A gas at room temperature, often stored under pressure as a liquid.
Anhydrous = without water (no water added)
Aqueous ammonia is ammonia with water (such as household ammonia cleaner). Risks associated with aqueous ammonia are relatively low.
Discuss how ammonia refrigeration system safety is governed by OHS and related laws in BC.
Ammonia refrigeration systems are a concern because they contain large quantities of anhydrous ammonia, they are typically in large urban areas, and they are complex mechanical systems with potential for failure.
WorkSafeBC has a combination of performance-based and prescriptive regulations for all toxic process gases
Technical Safety BC has detailed prescriptive regulations for boilers, pressure vessels, and refrigeration systems. These include:
- Mandatory standards of equipment design
- Mandatory standards of equipment installation
- Qualified operators and maintenance staff
What workplaces and work processes commonly use chlorine?
Disinfectant (swimming pool, water treatment plant, sewage treatment, community water supplies)
Also used in some manufacturing:
Pulp/paper industry, pool chemical products, cleaning products, mining processes, bleach manufacturing, plastics manufacturing.
What are health effects of chlorine overexposure?
- Nose/throat irritation
- Pulmonary edema
- Coughing, shortness of breath, dyspnea
- Onset of chronic asthma
- Corrosive burns (skin/eyes)
- Cold injuries with liquid contact
How are bulk quantities of chlorine usually transported?
Large pressurized containers on rail cars or tank trailers.
Alt - large volume pressure cylinders.
What is required for day-to-day safe work procedures when working with chlorine?
OHS and public safety regulators have regulations that require/enforce:
Design standards for equipment Design standards for facilities Qualification for workers Safe work procedures for work and emergency response Exposure control plans
What is anhydrous chlorine?
Chlorine, Cl is a diatomic molecule. Meaning that there are two atoms in one molecule: Cl2.
It is a gas at room temperature, and often stored under pressure to store in liquid form (anhydrous chlorine).
Sodium hypochlorite is a solid powder that can be dissolved into water to make bleach. Some chlorine gas is released from sodium hypochlorite/bleach in quantities that are generally considered to be safe.
What is the Transport Canada Emergency Response Guide?
The ERG is a reference guide that categorizes hazardous materials and gives important information on each category.
The information provided for each category is reliable and useful for the development of safe work and emergency procedures.
What certification/training is legally required for persons working with chlorine in Canada?
There are several good certification/training programs in Canada.
These programs are not required by any prescriptive legislation.
Legislation does require that workers be “qualified” and so due diligence requires that these programs of an equivalent be used.
Describe the health effects of inhalation of hydrogen sulphide.
Odor.
Irritation - eyes, nose, mouth, throat, lung. Loss of appetite.
Loss of smell
Headache, dizziness, ataxia, collapse.
Respiratory paralysis, cardiac arrhythmia, death.
How H2S is formed?
1, organic material
2, anaerobic conditions
3, sulphate-reducing bacteria
= H2S
Explain the role of OHS regulators and energy boards in regulating worker exposure to hydrogen sulphide
H2S is covered by broad hazardous material OHS laws, and a few specific H2S regulations in known high-risk industrial activities (oil & gas).
National and provincial energy board regulators, in their activities to protect public safety, indirectly improve worker safety.
Note:
- BC Oil and Gas Commission
- Canada Energy Regulator
What is hydrogen sulphide?
H2S
Usually a gas (unless under high pressure or extreme cold)
Highly toxic
In tiny amounts, has a rotten egg/sulphur smell
H2S is typically a by-product of other processes
H2S is created by anaerobic decomposition of organic material
Rapidly dissolves in water (or mucus membranes) to produce sulphuric acid.
What is sour gas?
Natural gas mixed with H2S.
The natural gas industry processes sour gas to remove H2S.
What is the usual H2S ceiling?
The ceiling limit for hydrogen sulphide is 10 parts per million.
C 10 ppm
No worker, at any time, for any duration, may be exposed to more than 10 ppm.
What is the H2S IDLH?
The Immediately Dangerous to Life or Health limit for hydrogen sulphide is ~100 ppm
What are the health effects of hydrogen sulphide?
Inhalation:
Airway irritation, pulmonary edema, headache, respiratory paralysis, unconsciousness, death.
Long term effects may cause asthma, RADS (reactive airway dysfunction syndrome), nervous system dysfunction.
Skin contact:
Cold effects from liquid form.
Eye contact:
Irritant. Cold effects from liquid form.
Not known to be carcinogenic, teratogenic, embryotoxic, reproductive toxin, mutagenic.
What is the rule of thumb for H2S concentrations?
1-10-100-1000ppm
1= Smell 10= Irritation (Regulatory limit) 100= Severe nose/throat/lung irritation, loss of appetite (severe enough to prevent self-rescue) 1000= Respiratory paralysis, arrhythmia, death
(around 150ppm, sense of smell stops working)
What workplaces may have H2S? (Name 4/7)
Gas plants, refinaries, petro-chemical plants, sulphur recovery plants.
Underground mines
Tank cars (railway), tank trucks (road)
Commercial laboratories
Septic tanks, sewers, manure handling areas
Pulp & paper mills
Pipelines
What is the LEL? (context, fire risk)
LEL = Lower Explosive Limit
The lowest concentration (%) of a gas or vapour in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat).
Sometimes called the Lower Flammable Limit.
Percentage vs ppm
1% = 10,000 ppm
What is the UEL? (context fire risk)
UEL = Upper Explosive Limit
The concentration (%) above which a gas will not burn.
What is the flammable range? Specifically for H2S.
The flammable range, is the range between the LEL and the UEL.
H2S has a range of 4 - 44.
(4% to 44%)
What H2S-specific sections are in the BC OHS Regulation?
The only H2S-specific regulations are under part 23, Oil and Gas.
What H2S-specific sections are in the BC OHS Regulation?
The only H2S-specific regulations are under part 23, Oil and Gas.
Why do most OHS regulations in Canada not have specific H2S sections in industries where H2S is a known hazard?
While there are not specific H2S sections/requirements, the general requirements for chemical hazards and confined space hazards provide sufficient regulation that would include H2S hazards.
List 5 areas of regulation (OHS & public safety) that apply to H2S, anhydrous ammonia, and chlorine gas.
- Design standards for equipment used in processes.
- Design standards for process facilities.
- Mandatory or highly recommended qualifications for workers who operate processes.
- Requirement for safe work procedures for normal work and emergency response.
- Exposure control plans.
Why might management of a H2S OHS program be potentially more challenging than for ammonia or chlorine?
There are uncertainties about the presence and quantity of H2S in a given situation.
Emergency scenario’s involving release and exposure of H2S can be sudden and with severe consequences.
How should an OHS program for H2S be started/approached?
1, Read the regulations and the ‘nearly law’ best practices carefully/completely.
2, Read the guidance documents from OHS and energy board regulators carefully/completely.
What is the maximum recommended short term exposures to H2S in a given day per the ACGIH?
5.
The ACGIH recommends no more than 5 short term exposures to H2S in a day.
American Conference of Governmental Industrial Hygienists.
How many breaths of high H2S concentrations are necessary to kill a worker?
1.
Name three broad areas of regulation for H2S.
1, General OHS regulations for hazardous materials.
2, Specific OHS regulations for activities where H2S is a known hazard.
3, Public safety laws, such as those administered by energy boards.
Why would a worker remain in an area of high H2S concentrations when there is a distinct/nauseating odor?
At high levels, H2S dissolves into the blood and paralyses the olfactory part of the brain, eliminating the sense of smell. Workers may be unaware of the high levels.
What is upstream or downstream oil and gas production?
The oil and gas production supply chain is divided into three areas: upstream, midstream, downstream.
Upstream - identification, extraction, and production of raw materials
Downstream - Post production of crude oil and natural gas
Midstream - Connects up/down stream. Transportation & storage.
What is H2S Alive?
A 1 day course offered by ENFORM for people entering the oil/gas industry. Covers H2S safety.
It is nearly impossible to work in upstream oil and gas without this course.
List three energy regulators that indirectly improve the safety of oil & gas workers.
The Canada Energy Regulator
Alberta Energy Regulator
BC Oil and Gas Commission
All three enforce laws to protect the public, which also result in worker protection.
What is part 5 of the BC OHS regulation?
Chemical agents and biological agents.
What is part 6 of the BC OHS regulation?
Substance specific requirements.
What jurisdiction is responsible for the transport of hazardous materials across provincial borders?
Federal, transport Canada.
What justification is responsible for transportation of hazardous materials on roads within a province?
Provincial. CVSE in BC
Commercial vehicle safety and enforcement
What justification is responsible for the use of hazardous materials in an RCMP lab?
Federal, labor Canada.
What justification is responsible for hazardous materials at a local hospital?
Provincial, WorkSafeBC
What justification is responsible for disposal of hazardous material waste at local landfill?
Provincial, ministry responsible for environment.
What does WHMIS stand for?
Workplace hazardous material information systems
What is WHMIS - explain to a worker.
Required at every workplace in Canada
A system to provide information to workers about hazardous materials they work with/around
Requires that workers using hazardous materials (hazardous products in legislation, previously controlled products) be educated and trained
Requires workers to be educated on the WHMIS elements (labels, SDS)
Requires that workers are trained in the safe use of hazardous materials and appropriate PPE.
Requires that workers be trained to respond to accidents and spills involving hazardous materials.
Describe common uses of ozone in the workplace.
- Swimming pool water treatment
- Drinking water disinfection (bottled water)
- To prevent food from spoiling (example ozonated ice)
Other Uses:
- Waste water treatment
- Cooling tower water treatment
- Treatment of storage water, fishing industry
- Purifying feed water in fish farming
- Disinfection (abattoirs, aquariums, hospitals)
- Pulp bleaching
- Medical treatments
- Perfume manufacturing
- Odour and smoke control
- Air purifiers
List health effects associated with overexposure to ozone.
Acute
Minor irritation of eyes & URT (low due to low water solubility)
Irritation of LRT (often described as a dull chest pain)
Headache
Pulmonary edema with higher concentrations
Chronic (either chronic low exposure, or chronic symptoms after a high exposure)
Reduced lung function, possible premature aging of body.
No evidence of carcinogenicity, or fetal-toxicity.
Explain the concept of a lower respiratory tract irritant.
There are fewer nerves in the lower respiratory tract than in the upper. Irritation of the LRT often feels more like a dull ache/pain than the true irritation of the URT.
Ozone is more of a LRT irritant than URT. As such workers may be less aware of symptoms if they are exposed.
Discuss similarities between ozone and chlorine as hazardous materials.
Both gasses, and toxic process gasses.
Both cause severe respiratory damage and can be fatal.
Both oxidizing agents, and can be used for disinfection.
Both can be used for disinfection of things like drinking water, in which case large quantities used.
Both have similar regulations and require similar control systems.
Describe common technologies used to generate and destroy large quantities of ozone in the workplace.
The most common system to use ozone:
- Water content of air decreased in an air dryer.
- Dry air moved into ozone generator (most commonly corona discharge). O2 breaks down and some O3 formed
- Compressor moves O3 through an injector into contact tank
- O3 meets water in contact tank, disinfection process
- Excess O3 released from contact tank into ozone destructor, where it is catalysed into O2
- Water from contact tank passed through de-ozoning filters and ready for use.
What is ozone?
O3.
A gas under normal circumstances, heavier than air.
Extreme pressure/cold required to liquify (not normally done)
Toxic process gas.
It is part of the smell after lightening.
Electricity can separate O2 molecules, allowing them to reform as O3.
Stratospheric ozone is the earth’s ozone layer. (good)
Ground ozone is an industrial pollutant which can cause environmental damage. (bad)
Ozone used in the workplace is good and bad. It has practical (good) uses, and can be harmful in excess or when not controlled (bad).
Discuss differences between ozone and chlorine.
Chlorine is almost never made on-site. It must be transported and stored. Ozone can be made on-site and is not stored in large quantities.
Chlorine is more water soluble than ozone. This makes it more of an upper respiratory tract irritant than ozone.
List 7 properties of ozone.
Gas at normal temperature/pressure
Heavier than air
Pungent odour
Excellent disinfectant
Blue in pure form
Invisible when in air
Highly reactive
What pictograms apply to ozone?
Health hazard
Oxidizer
Environmental Harm
Exclamation Mark (irritant & toxic)
List 4 properties of ozone as a disinfectant.
Used before other disinfection methods in system.
Greater effectiveness than other methods.
No residue in water.
Ineffective against algae at standard concentrations.
List 4 properties of chlorine as a disinfectant.
Used as last disinfection method in system.
Used in many forms as a disinfectant.
Leaves residue in water.
Effective against algae.
Discuss ozone generated from UV radiation.
A small amount of ozone is produced, and is typically used to disinfect small quantities of water.
Discuss ozone produced from corona discharge.
A high voltage of electricity is passed through a point, resulting in the electrical potential breaking down the molecules surrounding the point. Bluish light produced (the corona), and ozone formed.
Dried air is typically used to reduce unwanted products of reaction.
Discuss ozone desctructors.
A device or oven that used a catalytic process to convert ozone gas into harmless oxygen.
This permits for safe venting into the environment.
Discuss de-ozoning filters
Filters that will remove excess ozone in the ambient air or prior to entering target water source.
What is an ozone contact tank?
A container where ozone is allowed to contact water.
What is the ACGIH?
The American Conference of Governmental Industrial Hygienists.
That is TWA?
Time-Weighted Average.
The term is used to describe the exposure limit (ppm) for workers assuming an 8-hour work day and 40-hour work week.
What is OEL?
Occupational Exposure Limit.
What is the typical OEL for ozone?
TWA for heavy work is 0.05 ppm.
TWA for moderate work is 0.08 ppm.
TWA for light work is 0.1 ppm.
There are usually no prescriptive ceiling limits or 15 min exposure limits for ozone.
What is the IDLH generally reported for ozone?
Typically 5 ppm.
Discuss routes of exposure with ozone.
`Ozone exposure is typically considered to be through inhalation.
Absorption is generally not an issue. Ozone is not very water soluble, and direct contact would require high levels of exposure over time to break down the surface layers of the skin enough to cause any significant harm.
Ingestion is not likely due to the nature of the gas and it’s insolubility.
Discuss symptoms of ozone exposure at different concentrations.
The effects are dependant upon breathing rate/volume. As such effects under heavy work conditions are worse than light work conditions.
0.01 ppm - Odour threshold
0.1 ppm - Minor eye, nose, throat irritation
0.2 ppm - headache, dry cough
0.6 ppm - chest pain (dull)
1 ppm - Lung irritation, coughing, severe fatigue
5-10 ppm - IDLH
What is the ATSDR?
The Agency for Toxic Substances and Disease Registry (American)
What is the LEL and UEL of ozone?
LEL = Lower Explosive Limit UEL = Upper Explosive Limit
Ozone has neither, it is not flammable. It is however oxidizing, and so there is a fire risk.
Discuss laws related to ozone safety.
Ozone is not likely to cause a public health hazard, so public health laws are not a concern as they are for chlorine or ammonia.
Ozone is covered under general hazardous material regulations, and toxic process gas regulations.
There are no ozone-specific laws in Canadian OHS legislation.
What elements are included in safety guidelines for workplace ozone safety?
- Design standards for equipment
- Design standards for facilities
- Training/qualifications for workers
- Written safe work procedures and emergency procedures
- Exposure control plans
- Use of supplier manuals for equipment
What is the CRBOH?
The Canadian Registration Board of Occupational Hygienists.
What key engineering controls would be expected in a facility where ozone is generated in large quantities to disinfect drinking water?
- Ozone monitors (working room and vent post ozone destroyer)
- Interlock system between monitors/generator/destruct unit
- Ventilation systems in generator and filler rooms
What is Silica?
SiO2
Silicon dioxide, a chemical compound.
One of the most commonly occurring minerals on earth.
Usually a major component of sand. Quartz is silica.
What is silicon?
Si
Silicon
A chemical element.
Hard, brittle, crystalline solid.
8th most common element in the universe, and is rarely found in pure form in the earths crust.
What is silicate?
Any anion of silicon and oxygen.
Often used to denote types of rock that a predominantly composed of silicon oxides.
Silicates constitute the majority of the earths crust. (eg, sand)
What are the differences between crystalline and amorphous silica?
Crystalline silica is always more toxic than amorphous silica.
What is crystalline silica?
Any compound of silicon dioxide that has a regular structure.
What is amorphous silica?
Any compound of silicon dioxide that has an irregular structure.
What workplaces and activities are at highest risk of crystalline silica dust overexposure?
Trade contractors (construction)
Building construction
Heavy and civil engineering construction
Metal ore mining
Cement and concrete product manufacturing
What are silicones?
Silicones are polymers including any inert compound of repeating siloxane units.
Siloxane units are chains of alternating Si and O atoms.
Si-O-Si-O-Si
Name a type of silicate mineral that is a famous hazardous material.
Asbestos.
What is siloxane?
A siloxane is a compound including alternating chains of silicon and oxygen atoms.
Eg, Si-O-Si-O-Si
Differentiate crystalline and amorphous solids.
Both are solids, and so there are atoms fixed in position with each other that vibrate.
Crystalline solids form repeating patterns, where the patterns of connected atoms all look the same (crystals, metals, salts).
Amorphous solids form irregular patterns, where the sections of atoms each look differently. (glass, wax)
Compare the risks of silica exposure in processing silica sand versus making glass.
Both of these processes involve working with silica.
Silica sand is a crystalline silica, whereas glass is an amorphous silica.
The crystalline silica is more toxic than the amorphous form, as such the risks for the silica sand processing are higher than the making of glass.
Discuss diatomaceous earth.
Diatomaceous earth is a siliceous sedimentary rock consisting of fossilized diatoms.
It is an amorphous silica in it’s natural state which is not very toxic.
It can be exposed to high heats to change it into a crystalline silica called “calcined diatomaceous earth”. This is more toxic and is often used as a ine filtration medium (example, in pool filters).
Discuss “total”, “inhalable”, and “respirable” as occupational hygiene terms.
These terms all refer to the size of molecule where they can enter into the respiratory tract and cause illness.
Total, means the maximum size where the particle will cause illness (typically 100 microns and smaller)
Inhalable means the particles are small enough that they will pass the upper respiratory tract and enter the middle respiratory tract.
Respirable means the particles are small enough to pass to the lower respiratory tract and alveoli. (typically under 5-10 microns)
What pictograms are applicable to silica?
Harmful to health.
No others.
