Bioaerosol emissions from waste composting and recycling

Transcription

1 Bioaerosol emissions from waste composting and recycling Brian Crook IAPSC Meeting, December 2016

2 Overview 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.

3 Overview 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.

4 Overview 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.

5 Composting Commercial composting Compost handling dust, bioaerosol generation; noise; physical risks; odour.

6 MRF Materials Recycling Facilities (MRF) Materials reception; Some automatic sorting

7 MRF Materials Recycling Facilities (MRF)..But a lot of manual sorting; Some LEV but not always.

8 Health risk 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.

9 Measurement 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.

10 HSL report Results of HSL research Exposure levels HSL s recent work: Workers personal exposure; Deriving source terms for modelling dispersion; Measuring levels at different distances downwind to validate models and establish risk zones.

11 HSL report 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

12 HSL report 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/m 3 Aspergillus fumigatus fungus spores and a 4% chance of being exposed to more than 1 million cfu/m 3 Aspergillus fumigatus spores.

13 HSL report 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/m 3 and 17% chance that exposure to airborne Aspergillus fumigatus spores will be more than 1,000 cfu/m 3.

14 HSL report 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/m 3.

15 HSL report 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.

16 MRF project 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.

17 MRF project HSL study in MRFs what we did Data available from HSE Research Report series ( esearch/rrhtm/rr977.htm)

18 MRF project 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 mg/m 3 ; Seven (5%) of the exposures were above the 8-hr TWA inhalable dust limit set at 10 mg/m 3.

19 MRF project Workers potential endotoxin exposure 8-hr TWA exposures to endotoxin ranged from less than the LOD to 2399 EU/m 3 (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)/m 3 ; The majority of the exposures over 90 EU/m 3 were measured at MRFs that used high energy sorting machinery.

20 MRF project Other potential microbial exposure Exposure to inhalable bacteria ranged from 10 2 to 10 5 cfu/m 3. None was greater than 10 6 but 102 (73%) exposures were greater than 10 4 ; Exposure to inhalable fungi ranged from 10 2 to None was greater than 10 6 but 113 (81%) were greater than 10 4 ; Exposure to Aspergillus fumigatus ranged from less than the LOD to (12%) were greater than 10 4 and a further 20 (14%) greater than 10 3.

21 MRF project 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.

22 Summary 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.

23 Summary 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?

24 Summary Current and future bioaerosol research HSL currently completing exposure study of workers in biomass handling municipal waste transfer stations, mechanicalbiological treatment plant materials handling areas; At one, compared day shift routine cleaning with night shift cleaning and maintenance); Daytime : endotoxin from EU/m 3 ; bacteria 4.0 x x 10 4 cfu/m 3 ; fungi 8.0 x x 10 5 cfu/m 3 ; Night-time : endotoxin from !! EU/m 3 ; bacteria 2.6 x x 10 5 cfu/m 3 ; fungi 1.1 x x 10 5 cfu/m 3.

25 Summary 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.