Monitoring of Diesel Exhaust Particulate (DEP)

Transcription

1 Health and Safety Executive Monitoring of Diesel Exhaust Particulate (DEP) 28 th September 216 James Forder HSL: HSE s Health and Safety Laboratory Crown Copyright, HSE 216

2 Introduction What is Diesel exhaust particulate (DEP)? Constituent of diesel engine exhaust emissions, alongside, CO, CO 2, NO x, aldehydes, PAHs 2 main components, organic carbon (OC) and elemental carbon (EC) Nanoscale particles which agglomerate into clumps and chains Why monitor DEP? IARC classify it as a definite human carcinogen More specific and correlated with diesel engine exhaust emissions than the other main constituents.

3 Super short summary of a literature review commissioned by HSE Health effects Acute respiratory/eye irritation, rare for exposures below 1 µg/m 3 EC Persistent - lung cancer, rhinitis and cardiac illness. Evidence is currently insufficient to establish links with adult onset asthma and COPD.

4 Super short summary of a literature review commissioned by HSE Occupational exposures (from IARC monograph, 213) Transport, typically < 5 µg/m 3 EC Mining, 1 6 µg/m 3 EC Construction, main exposures in tunnelling works

5 Super short summary of a literature review commisioned by HSE Measurement EC mass by combustion is the most appropriate measurement to assess exposure to DEEEs Biomonitoring of nitro- and amino-pyrenes Increase in ultrafines (<4 nm) in modern biodiesel engines. Particulate mass (EC) may underestimate health effects

6 Elemental Carbon EC is favoured as a marker for DEP Thought to be highly specific to diesel exhaust Other carbon sources can be removed by size selection at the inlet Some evidence that the nanoscale physical nature of the particles are a cause of observed health effects Image courtesy of Tomas E Baquero Rincon, University of Sheffield

7 Established methods The standard method is codified in EN1453:24 and NIOSH method 54. The methods are not equivalent but incorporate the same key stages. Sample on to quartz fibre filters with cyclonic samplers, Heat the filter to temperature 1, measure the evolved CO 2 = OC. Increase the temperature, measure the evolved CO 2 = EC

8 Established methods Being a carbonaceous soot DEP is black, therefore the degree of staining can be used to quantify exposure. Historically, for on-site monitoring the blackness of sample filters has been measured using the Bosch meter. Blackness can be converted to EC.

9 Previous work at HSL Alternatives to the Bosch meter 3 techniques analogous to measuring blackness Difference gloss meter (DR-Lange) Scanner/photo software OT21 transmissometer (Magee Scientific) Filters collected form Mobile crane exhaust Ambient air in a mine All 3 methods could replace the Bosch meter. In principle any optical technique could be used.

10 EC (µg on filter) Earlier work at HSL Charts were prepared showing the correlations between each instrument and EC. Functions were derived to convert the instrument results to EC. Difference gloss meter EC = 1 (-.244x ) Scanner (greyscale) EC = 1 (-.65x ) OT21 transmissometer EC = 1 (.2x -.795) Mine air Crane exhaust -1-5 Difference gloss meter Scanner OT21

11 Modernising & Improving Results post shift is good but wouldn t results during a shift be better? Highlight specific exposure sources Facilitate and encourage immediate interventions Empower workforce A B A B C D

12 Real-time monitoring Incorporate pump, sampler and measurement in one device. Several options. General particle counters Readily available Non-specific, result is number of particles not mass of EC FLIR Systems Airtec Developed to replicate NIOSH 54 Light absorption measurement technique Result given is EC based on a calibration study AethLabs AE51 microaeth Developed for ambient air measurement Miniaturised version of OT21 measurement technique Result is Black carbon

13 Real-time monitoring HSL has been studying the performance of the µaeth and Airtec in parallel sampling tests with filters analysed by EN1453. A controlled atmosphere of diesel exhaust has been prepared and measured in the laboratory. In addition the instruments have been tested in field trials in a variety of workplaces. RO-RO ferries Vehicle test station Underground non-metal mines

14 -1-5 Fitted air concentration ( 5 1 g/m 2 3 ) 1 g/m 15 3 ) Laboratory measurements Time from start of test (mins) Airtec BC Time from start of test (mins) Airtec BC 95% CI 95% CI

15 12:57: 12:59: 13:1: 13:3: 13:5: 13:7: 13:9: 13:11: 13:13: 13:15: 13:17: 13:19: 13:21: 13:23: 13:25: 13:27: 13:29: 13:31: 13:33: 13:35: 13:37: 13:39: 13:41: 13:43: 13:45: 13:47: 13:49: 13:51: 13:53: 13:55: 13:57: 13:59: 14:1: 14:3: 14:5: 14:7: 14:9: 14:11: 14:13: 14:15: 14:17: BC/EC (µg/m^3) On site measurements 2 1 min comparison µaeth Airtec Mine Airtec 4 2 Time

16 Air Concentration of of Airtec EC Air concentration of µaeth BC Instrument performance µaeth AE51 µg.m y = 1.845x R² =.999 µaeth (BC) 1:1 Relationship Air Concentration of EC by EN1453 method µg.m -3 Airtec µg.m y = 1.185x R² =.7417 Airtec EC 1:1 Relationship Air Concentration of EC by EN1453 method µg.m -3

17 Usefulness of gas monitoring Measured CO, CO 2, NO, NO 2 alongside particulates. HSG 187 states that if CO 2 is <1 ppm DEEE exposures are likely to be low. This should not be relied upon. CO - unmeasurable. CO 2 confounding sources, low resolution NO and NO 2 low resolution, can correlate with particulates, urban background often more significant

18 Usefulness of gas monitoring NO2(ppm)(Max) 13:8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14:28 NO(ppm)(Max) 13:8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14:28 13:8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14: CO(ppm)(Max) CO2(ppm)(Max) :8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14:28

19 Usefulness of gas monitoring NO2(ppm)(Max) 24, 19, 14, 9, 4, BC :8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14:28 NO(ppm)(Max) 13:8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14:28-1, 12:56 13:4 13:12 13:21 13:29 13:37 13:46 13:54 14:2 14:11 14:19 CO2(ppm)(Max) :8 13:18 13:28 13:38 13:48 13:58 14:8 14:18 14:28

20 Real-time monitoring - Conclusions Airtec Advantages Can sample for a full shift at high concentrations On board display Limitations Slow response time not truly real time High limit of detection, especially for short term sampling AE51 microaeth Advantages Low detection limits Quick response Limitations Short monitoring period at high concentrations Does BC = EC? Separate device required to view results in real-time

21 Summary Diesel exhaust is unhealthy Most UK occupational exposures are low Levels in the general environment are also significant Real-time monitoring is possible using black carbon as a proxy. Research interest globally

22 Improved microaeth instruments Now in 3 formats, two personal monitors, one static tape filter drive (for extended sampling and analysis), multi wavelength capabilities (allowing assessment of organic carbon, brown carbon e.g.woodsmoke/tobacco derived carbon in addition to black carbon) dual spot sampling (internal correction of self absorption) GPS and Wifi/Bluetooth capabilities (for data transfer to PC/Tablet/phone etc.) Weather-proof version for fenceline/lamp post/static sampling (unattended monitoring for up to 3 months)

23 Acknowledgements/Further reading This work was funded by the Health and Safety Executive. Its contents, including any opinions/conclusions expressed, are those of the author alone and do not necessarily reflect HSE policy. HSE RR994, available from the HSE website Simply Scan published in the Annals of Occupational Hygiene, 214, vol 58, AethLabs AE51 µaeth - FLIR Airtec -

24 HSL HSE s Health and Safety Laboratory HSL is the commercial arm of the Health and Safety Executive, HSE. Our commercial work delivers high quality science to meet the needs of industry and government in the UK and overseas. Our commercial customers can commission services and research using our state-of-theart scientific laboratory in Buxton, as well as analytical expertise from other parts of HSE s science base.