HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016 HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Brian Crook
IAPSC Meeting, December 2016
Bioaerosol emissions from waste composting and recycling
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
What this talk will cover
Bioaerosols and bioaerosol exposure;
Bioaerosols in the context of waste and recycling;
Example 1 - Occupational exposure to compost bioaerosols and downwind dispersion;
Example 2 – Materials Recycling Facilities;
Current and future HSE/L Waste & Recycling Programme.
Overview
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Sources of bioaerosols
Bioaerosols always naturally present from various sources – dust, water, vegetation, animals;
Range in numbers and predominant species – seasonal, geographic, local sources;
Further influenced by human activities – agriculture, construction, vehicles.
Overview
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Bioaerosols in the context of waste & recycling
Waste & recycling – economic, conservation and legal drivers;
Some areas of work automated, but some manual input;
Waste & recycling involving organic materials – energy input to processes will generate dust and bioaerosols.
Overview
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Commercial composting
Compost handling – dust, bioaerosol generation; noise; physical risks; odour.
Composting
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Materials Recycling Facilities (MRF)
Materials reception;
Some automatic
sorting……
MRF
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Materials Recycling Facilities (MRF)
…..But a lot of manual sorting;
Some LEV but not always.
MRF
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Waste & recycling bioaerosols and health – Aspergillus fumigatus and endotoxin
Workers’ exposure to bioaerosols;
Dispersion neighbours (other workplaces, passers by, residents).
Why are we concerned about Aspergillus fumigatus?
Prolific spore producer;
Spores are respirable;
Allergen, opportunist pathogen.
Why are we concerned about endotoxin?
Gram –ve bacterial cell wall;
Immunotoxic;
Cause inhalation fever.
Health risk
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Dust and bioaerosol measurement in waste & recycling
• Air sampling – methods used by HSL • Seven MRF facilities once each; • Six composting facilities, fourteen site sampling visits at
different times of year; • Inhalable and respirable dust; bioaerosol exposure with
‘exposure banding’.
Measurement
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Results of HSL research
Exposure levels – HSL’s recent work: http://www.hse.gov.uk/research/rrhtm/rr786.htm
Workers’ personal exposure;
Deriving source terms for modelling dispersion;
Measuring levels at different distances downwind to validate models and establish risk zones.
HSL report
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Risk Zones (HSL Report data)
• Red zone – next to composting activity;
• Amber zone – within 50m
• Yellow zone –50 to 100m
• Green zone –100 to 250m
• Green box – background 50m+ upwind
HSL report
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Red zone exposure data
If you are working next to composting handling machinery and not protected within a vehicle cab:
There is a 24% chance of being exposed to more than 100,000 cfu/m3 Aspergillus fumigatus fungus spores and a 4% chance of being exposed to more than 1 million cfu/m3 Aspergillus fumigatus spores.
HSL report
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Green zone exposure data
Nearer the site boundary, that is, 100 to 250 metres from composting:
There is only a 2% chance that exposure to airborne Aspergillus fumigatus spores will be more than 5,000 cfu/m3 and 17% chance that exposure to airborne Aspergillus fumigatus spores will be more than 1,000 cfu/m3 .
HSL report
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Background exposure data
Beyond the site boundary, at least 50 metres upwind from composting:
No samples of airborne Aspergillus fumigatus spores yielded more than 1,000 cfu/m3 .
HSL report
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Protection afforded by vehicle cabs
Measured bioaerosols inside and outside cabs;
Bioaerosol levels reduced inside cabs – variable but with a median value of a four-fold reduction ;
Suggests need for further examination.
HSL report
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
HSL study in MRFs –what we did
Occupational hygiene surveys at seven MRFs. Each visit aimed to measure task- related exposures to dust and bioaerosols at all stages of the recycling process mainly by personal monitoring;
In addition, exposure control strategies assessed including management systems (COSHH assessments, operator training etc.), engineering controls and the PPE regime.
MRF project
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HSL study in MRFs –what we did
Data available from HSE Research Report series (http://www.hse.gov.uk/research/rrhtm/rr977.htm)
MRF project
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Workers’ potential dust exposure
139 exposures measured for inhalable dust and micro-organisms during periods representative of typical working conditions;
8-hr TWA exposures to inhalable dust ranged from 0.15 to 22.63 mg/m3;
Seven (5%) of the exposures were above the 8-hr TWA inhalable dust limit set at 10 mg/m3.
MRF project
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Workers’ potential endotoxin exposure
8-hr TWA exposures to endotoxin ranged from less than the LOD to 2399 EU/m3 (8hr TWA);
47 (34%) were above the 8hr TWA health based occupational exposure limit proposed by DECOS for airborne endotoxin of 90 endotoxin units (EU)/m3;
The majority of the exposures over 90 EU/m3
were measured at MRFs that used high energy sorting machinery.
MRF project
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Other potential microbial exposure
Exposure to inhalable bacteria ranged from 102 to 105 cfu/m3. None was greater than 106 but 102 (73%) exposures were greater than 104;
Exposure to inhalable fungi ranged from 102 to 105. None was greater than 106 but 113 (81%) were greater than 104;
Exposure to Aspergillus fumigatus ranged from less than the LOD to 105. 17 (12%) were greater than 104 and a further 20 (14%) greater than 103.
MRF project
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Occupational hygiene data
Risk assessments had either not been carried out or were in need of review at most sites;
None of the 7 sites used LEV inside the sorting stations effectively to reduce operator exposure;
One site had LEV with capturing hoods placed in areas where potential for dust generation, but exposures measured were among the highest, indicating limited effectiveness as a measure to control exposure;
Use of respiratory protection was sporadic and the protective effect of the masks used was limited.
MRF project
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
What this adds to current data - composting
Compost bioaerosol exposure levels – from HSL’s study:
Workers’ potential personal exposure;
Task-specific bioaerosol exposure data;
Possible protection afforded by vehicle cabs;
‘Risk zone’ approach applicable on sites;
Deriving source terms for modelling downwind dispersion;
Measuring levels downwind to validate models.
Summary
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
What this tells us about MRFs
Large proportion of manual work handling waste materials;
Workers’ potential personal exposure to dust and potentially allergenic bioaerosols;
Exposure controls are basic;
WHAT ABOUT OTHER WASTE AND RECYCLING FACILITIES, AND EMERGING ENERGY TECHNOLOGIES SUCH AS BIOMASS TO ENERGY?
Summary
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Current and future bioaerosol research
HSL currently completing exposure study of workers in biomass handling – municipal waste transfer stations, mechanical-biological treatment plant materials handling areas;
At one, compared day shift routine cleaning with night shift cleaning and maintenance);
Daytime : endotoxin from 127 -210 EU/m3; bacteria 4.0 x 103 – 4.4 x 104 cfu/m3; fungi 8.0 x 104 – 1.0 x 105 cfu/m3;
Night-time : endotoxin from 117 -1040!! EU/m3; bacteria 2.6 x 104 – 3.6 x 105 cfu/m3; fungi 1.1 x 105 – 4.0 x 105 cfu/m3.
Summary
HSL: HSE’s Health and Safety Laboratory © Crown Copyright, HSL 2016
Summary
Long-term high level exposure to bioaerosols causes respiratory health problems – lower level chronic exposure less obvious but still detrimental effect;
Composting bioaerosols disperse quickly with distance from source, so main effect is on workforce;
Control options are limited but need to used effectively;
Some tasks, such as cleaning and maintenance, can increase exposure.
Summary