The Health and Safety Executive recently released a report on bioaerosol issues at various municipal waste handling sites, including Mechanical Biological Treatment (MBT) plants, waste transfer stations, and Energy from waste (EFW) plants. The aim of this study was to better understand the risk of exposure to dust and bioaerosols whilst handling municipal waste, the bulk of which occurs on waste transfer stations, and on waste treatment plants. To highlight achievable control standards, the study only recruited companies that were seen to employ “reasonably good health and safety management practices”.
Bioaerosols are airborne particles or clumps containing biological material, such as microorganisms (like bacteria, fungi, and viruses), pollens, or cellular components (e.g. endotoxins). They are found in nature at low, harmless background levels. However, high concentrations of bioaerosols can be emitted by certain human processes – particularly those involving organic matter – and these concentrations can cause human health problems, including respiratory diseases such as asthma or bronchitis.
What were the findings & recommendations of the HSE report?
There were three activities that were discovered to pose a risk of higher bioaerosol exposure, and therefore presented health risks to workers. These were:
- Cleaning & maintenance – this often means workers are in closer contact with untreated waste, and certain methods (e.g. dry sweeping) can generate lots of airborne dust
- Automatic sorting and processing of waste, after waste had undergone bio-drying
- Hand-sorting waste to recover dry cell batteries from the waste stream
As such, bioaerosols and dust could be controlled by further enclosing sorting machinery and conveyor systems, to reduce the exposure risk for staff. Additionally, reducing the amount of cleaning needed (e.g. by preventing spills), and using cleaning techniques with lower levels of dust disturbance, should be considered.
Although bioaerosols main exposure route is through inhalation, there is also a risk of dermal exposure to waste, which could result in accidental ingestion of microorganisms through hand-to-mouth transfer. This can cause gastro-intestinal infections. This risk emphasises the importance of good hand-washing facilities, and an effective site lay-out that encourages workers to clean and change their clothing as they move through certain site areas.
The report recommended that operators of both MBT plants and waste transfer stations should measure the possible impacts of dust and bioaerosol exposure on their sites. Waste Transfer Stations are thought to present a higher risk due to there being more open waste. EFW plants, on the other hand, do not need to assess bioaerosol risks as their automated operations, and segregation of staff from dust and bioaerosols, means there is a low potential for exposure.
What does this mean for the waste management industry?
It is currently well-known that there are environmental bioaerosol risks associated with composting and Anaerobic Digestion sites, as is mentioned in the M9 Technical Guidance Note on bioaerosol monitoring. As such, many of these types of sites need to conduct environmental monitoring (especially if there are any sensitive receptors near the site). Environmental monitoring aims to measure the bioaerosol concentrations emitted into the external environment by following the M9 protocol.
However, this study from the HSE refers to occupational monitoring: the monitoring of bioaerosol concentrations that a site’s employees are exposed to. It is important to distinguish the two, so that operators of waste treatment facilities know which type of bioaerosol monitoring they are likely to need to ensure that their site is safe and compliant.
The companies involved in the HSE study all regularly monitored occupational exposure to inhalable dust, but none did so with bioaerosols. This identifies an area where companies may not be doing all that they can to ensure site safety. However, the HSE recognised that systematically assessing bioaerosol exposure can be complex and expensive, and so the fundamental requirement of waste transfer sites and MBTs is to “apply the hierarchy of control and employ good control practices in line with COSHH”.
The need to recycle an increasing proportion of organic materials is only rising, due to various Government targets, such as Scotland’s ban on all municipal biodegradable waste going to landfill by 2025. As such, it is likely to become more important for the waste treatment industry to conduct bioaerosol monitoring and bioaerosol risk assessments, so that waste operators are equipped to treat ever-increasing quantities of organic material whilst keeping their workers safe and healthy.
A summary of the lets recycle article can be found on letsrecycle.com, and the original HSE report is found here hse.gov.uk
Written by Jennifer Kowalski, Environmental Scientist at The Open University
