Inhalable Dust vs Respirable Dust | Air-Met Scientific
Dust is present all around us, in our workplace, homes and surrounding environment. Small amounts of dust are unharmful and will cause minor discomforts such as irritation of the eyes, coughing or sneezing. This can usually be resolved by opening a window to dilute indoor air with fresh outdoor air, having antihistamines or by using an indoor air filter
However, dust produced in an industrial setting such as during manufacturing or production processes are not so easily resolved. Industrial dust is hazardous to employees and for communities surrounding an industrial area due to its toxic and potentially combustible nature. Hazardous dust in industrial and construction settings are known to cause long-term chronic health effects to workers and the surrounding community which is why it is closely monitored by governing bodies such as Safe Work Australia to ensure the dust exposure levels are not exceeded.
Inhalable and Respirable Dust and its Control Measures
Depending on the particle size, dust is classified broadly under two categories: inhalable dust and respirable dust. Inhalable dust is smaller than 100 micrometres in size and affects the upper respiratory system including the mouth, nose, throat, and upper respiratory tract. Examples of inhalable dust sources include the grinding of metals such as lead-containing alloys and earth-moving activities in construction and remediation. Unlike inhalable dust, respirable dust cannot be seen in normal lighting as they are smaller than 10 micrometres in size. Due to their extremely small size, respirable dust particles can stay airborne for a significant amount of time and can be inhaled deep into the lungs causing irrevocable lung damage. Respirable dust sources include the grinding of hazardous metals containing silica and quartz or coal dust produced from the quarrying of coal.
Exposure to any dust for a prolonged period can be harmful and lead to a range of health problems. The effects of dust exposure can vary from skin irritation to lung cancer depending on the composition of the dust, the type of dust particle and the degree of the exposure. Airborne particles on the finer end of the respirable dust scale i.e., less than 10 microns, can cause inflammation of the heart, raising the probability of heart disease. Due to the range of hazards that can result from dust exposure in workplaces, the implementation of a range of control measures is required by businesses to ensure workers do not exceed certain exposure standards and limits.
Dust suppression controls for inhalable and respirable dust in the workplace include:
Continuous review of the effectiveness of existing control measures
Reviewing exposure levels after a process or production method has been modified
Investigating complaints by workers
Complying with advice or a notice of improvement issued by a regulator or occupational hygienist.
Depending on the industry and application, there are a range of useful controls and guidance advice by Safe Work Australia for monitoring dust exposure levels in the workplace. These include:
There are two Australian Standards that businesses are required to comply with when sampling the level of respirable and inhalable dust in workplaces. These are:
Respirable Dust: AS 2985 Workplace atmospheres – method for sampling and gravimetric determination of respirable dust
Inhalable Dust: AS 3640 Workplace atmospheres – method for sampling and gravimetric determination of inhalable dust
It is a legal requirement for businesses to provide a safe working environment for workers and to make sure the dust from their activities does not harm human health or the environment.
Dust monitoring in workplaces is often undertaken by occupational hygienists who assess and determine whether the concentration of contaminants present in the air is within safe exposure limits or verify the levels of dust exposure in the workplace. This allows businesses to ascertain the type of controls and plant practices that should be implemented to protect the health and safety of the workers.
Personal sampling devices such as the SKC Conductive cyclone are used to capture and separate smaller respirable particulates. The SKC cyclone should be clipped near the worker breathing zone and attached to a personal air sampling pump such as the AirChek Essential Air Sampling Pump. Inhalable particles can be collected with an SKC IOM Sampler attached to a personal air sampling pump.
Businesses are also required to comply to EPA guidelines to prevent inhalable and respirable dust exposure to the general public. Worksites are required to provide ambient air sampling measurements to conform to public safety standards. Ambient air is monitored using a real-time dust monitor such as the AirMetER-DX which can monitor PM10 and PM2.5 particulates.
