How to estimate the level of exposure of your workers to hazardous chemicals

Jan 17, 2019 Posted by Walter Ingles

 Business owners and operators must ensure that no one at their workplace or job site is harmed by chemicals or hazardous substances. This includes keeping airborne concentrations of chemicals within workplace exposure standards. Chemical exposure standards are set by Safe Work Australia and are identified in the Safety Data Sheet (SDS) which accompanies each chemical. This blog will help you understand the steps required when estimating chemical exposure levels and the potential harm to your workers. We’ll also discuss compliance with workplace exposure standards.

Estimating levels of chemical exposure

The severity of a chemical health hazard is impacted by a number of factors, and all of these must be considered in your risk assessment.

  • Possible routes of entry (petrol spilled onto the skin, ingested or inhaled vs diesel exhaust inhaled)

  • Toxicity of the chemical (Schedule 7 Dangerous Poison vs Schedule 6 Poison)

  • Quantity of the chemical (a worker pouring corrosive chemicals from a beaker into a test tube vs workers carrying out repairs to the lid covering a vat of corrosive chemicals)

  • Concentration (cleaning with 5% ammonia mixed with water vs pure concentrate)

  • Duration of exposure (1 hour per week for 10 years vs 8 hours per day for 1 month)

  • How the chemical is being used (pouring a pesticide into a container vs spraying a pesticide on crops)

  • Control measures already in place (PPE, exhaust fans, decanting stations, job rotation)

  • Whether personnel are working directly with the chemicals (workers decanting chemicals into smaller containers vs maintenance crew carrying out repairs adjacent to the decanting station)

  • Other chemicals being used (using an aerosol paint can in an isolated area vs using an aerosol spray can while operating an acetylene oxygen welder)

  • Individual health factors (worker 30 years old non-smoker vs worker 55 years old who has asthma and smokes)

  • Work history (new worker never exposed to chemicals vs worker who spent 10 years working with pesticides every day)

We suggest collating all the data listed above and compiling a chemical exposure profile for your risk assessment. In our example below we’ve indicated the exposure profile of a single worker, but this could also be prepared for work teams or by department eg, warehouse employees exposed to diesel exhaust.

Example 1: Worker X is using ammonia, a schedule 6 poison for cleaning. The ammonia is premixed to a concentration of 5% ammonia by a supervisor (so Worker X is never exposed to higher concentrations) and they clean for 3 hours per day (5 shifts per week). Worker X has been employed as a cleaner for 6 months and has never worked with chemicals before. He is a non-smoker and has no known allergies.

Cleaning is done in office buildings including toilets, cubicles, enclosed work spaces and meeting rooms. Most of the office buildings don’t have opening windows and the work is carried out in the morning before the air condition service is scheduled for operation. Worker X uses disposable latex gloves but no respiratory protection.

Methods of exposure testing

Your chemical exposure profiles will help you identify workers who could be at risk of dangerous chemical exposure, as well as create a priority list for exposure testing. There are a number of ways you can test work areas for the presence of airborne chemicals including:

  • Observation — simply looking for of evidence of airborne concentrations of chemicals. You might notice dust that has settled on people and equipment, mist or fumes visible in the air or against the light. The presence of chemical odours is also an indication.

  • Simple tests — using commercially available dust lamps, indicator tubes and strip tests to give you a better idea of what chemicals may be present in work areas.

  • Personal sampling — testing contaminants in the breathing zone of individual workers.

  • Static sampling — testing air-borne contaminants in work zones to establish high risk operations and hazardous trends.

  • Air monitoring — formal testing carried out by an occupational hygienist to ensure breathing zones are within workplace exposure levels and whether ventilation systems are operating correctly. In Australia air monitoring records must be kept for 30 years.

 REMEMBER: Exposure levels may vary throughout a shift and these tests only indicate the presence of chemicals and cannot reliably measure concentration levels.

Workplace exposure standards for hazardous chemicals

More than 700 hazardous chemicals have a Workplace Exposure Standard set by Safe Work Australia. If your workplace has these chemicals you must ensure that the air quality stays within the limits defined by the standards.

If you are using chemicals that have an exposure standard you will need to:

  1. Identify the chemicals and create an exposure profile for the workers using (or at risk of being exposed to) them.

  2. Collate the exposure profiles and tag high risk profiles for exposure testing.

  3. Carry out preliminary observations and tests in those work areas to detect the presence of air-borne contaminants.

  4. Introduce suitable control measures (ventilation systems, work methods, rosters)

  5. Carry out formal air monitoring to ensure air quality is within the exposure standards.

It is important to remember that chemicals can be absorbed through the skin you may also have to carry out biological monitoring of workers to ensure they are not being harmed by the chemicals.

REMEMBER: Keeping chemical concentration levels within workplace exposure standards is not a standalone control measure or even an indication of a ‘safe breathing zone’. Chemicals affect people differently and the presence of other chemicals and even the climate can impact how a worker’s health may be harmed.

Next steps

Learn how to include chemical exposure testing into your risk assessment by downloading our free eBook How to manage the risk of Hazardous Chemicals in the workplace. We introduce a complete risk management plan to minimise chemical hazards and fulfil your WHS obligations. Download and read it today by clicking on the image below:

How to manage the risk of hazardous chemicals in the workplace

Walter Ingles

Walter Ingles Compliance Specialist

Walter is STOREMASTA’s Dangerous Goods Storage Specialist. He helps organisations reduce risk and improve efficiencies in the storage and management of dangerous goods and hazardous chemicals.

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