Brian Davies University of Wollongong

Transcription

1 Brian Davies University of Wollongong

2 Origins of Diesel Particulate (DP) issue Health effects update Global trends Monitoring strategies Summary 2

3 Two fractions: Gaseous Major components (99%) N 2, O 2, Ar, CO 2 & H 2 O vapour Minor components (1%) CO, NO x, SO 2 & Hydrocarbons Particulate

4 Small particles (15-30 nm) called spherules Agglomerate to form larger particles (<1 μm in diameter) Absorb significant quantities of hydrocarbons and other organic compounds Have traces of inorganic compounds Respirable

5 Electron micrograph mine diesel particulates showing spherules, chains and agglomerates Schematic mine diesel particulate showing spherules, chains and agglomerates Source: A Rogers

6 NIOSH Current Intelligence Bulletin 50 (1988) Numerous animal studies involving mice, rats & hamsters exposed to whole diesel exhaust indicated increased levels of lung tumors in mice & rats and respiratory tract irregularities in hamsters (but no tumors) Human studies (US rail road workers) published in 1987 & 1988 showed a significant elevated relative risk for lung cancer (some confounding issues) 6

7 IARC in 1989 declared whole diesel exhaust category 2A (Probably Carcinogenic to Humans) based on limited evidence of carcinogenicity in humans coupled with sufficient evidence of carcinogenicity in experimental animals Studies by J L Mauderly & co-workers established the particulate component of whole diesel particulate to be biologically active in rats 7

8 Major epidemiological studies Long haul truck drivers increased risk of lung cancer but study limited due to lack of exposure data German potash miners study non significant positive trend with increasing exposure but some confounders Swedish bus garage workers increased risk but study limited by confounders (smoking) 8

9 Heath Effects Institute (HEI) in 1995 reviewed 30 epidemiological studies and concluded that the data was consistent in showing weak associations between exposure to diesel exhaust and lung cancer Two independent meta-analysis of published epidemiological studies (1998 & 1999) concluded significant elevated risk of lung cancer from exposure to diesel exhaust 9

10 MSHA (2001) suggested that at a mean concentration of 0.64 mg/m 3 DP (approximately 0.32mg/m 3 EC) for a period of 45 years exposure would result in a doubling of the risk of cancer compared to that of unexposed miners Issues of irritation (eyes, nasal & bronchial) identified 10

11 In May 2002 the US Environmental Protection Agency (EPA) concluded that lung cancer was evident in occupationally exposed groups but was unable to determine a degree of potency Regulatory response in many countries especially in over the road diesel vehicles. Some countries have introduced controls on DP in mines (Canada, Germany, USA) 11

12 Classified as carcinogenic by many authorities throughout the world (IARC) Potency not well defined but significant (probably similar to passive smoking) Small particle size of DP has resulted in it being linked to non malignant health effects Irritant (eyes, nasal & bronchial)

13 As engine design has changed in response to regulatory pressure there has been considerable investigation of non malignant heath effects Focus on particle size rather than particle mass Carcinogenicity of biodiesel questioned 13

14 Year Light Duty NOx (g/km) Light Duty DP (g/km) Heavy Duty NOx (g/km) Heavy Duty DP (g/km) 2000 Euro I Euro II Euro III 2010 Euro IV Euro V

15 > 90% less than 1 um Most of the mass is in the um accumulation size fraction Most the particles are in the <0.1um which are termed ultrafine nano-particles 15

16 Source: Prasad & Bella

17 Generally defined as particles less than 50nm (0.05 um) but massive surface area/unit mass Penetrate deep into the lungs Have been shown to cross into the bloodstream and are transported to all parts of the body including the brain Can accumulate in the lungs causing possible obstruction of oxygen transfer to the blood 17

18 Vegetable oils first used by Rudolf Diesel in late 1800 s While biodiesels decrease DP they can increase NO X Rape seed oil & rape seed oil methyl ester have shown a strong increase in mutagenicity (10 to 60 fold) over established diesel fuels Calls for research on the potential carcinogenicity of biodiesel 18

19 While carcinogenicity hasn t been forgotten the focus is clearly on non malignant health effects due to newer engine designs producing more & smaller particles Cardio vascular effects seen as major issue by major research bodies around world (especially for asthmatics) Some recent evidence (June 2011) that DP may induce inflammation effects in airways of rats 19

20 Nano-particle issue dominating research US National Cancer Institute & NIOSH Diesel exhaust Study in Miners Major retrospective epidemiological study Concerns due to focus on old engine technology (pre mid 1990 s) Historical exposure data a limiting factor (exposure data not collected systematically until late 1990s) 20

21 Mutagenicity of DP Samples collected under light load conditions mutagenic but not at heavy load Mutagenic activity absent post a DOC but present post a DPF Concluded mutagenic activity associated with volatile fraction absorbed onto surface of DP 21

22 Research has shown maintenance to be a major factor in controlling DP Canadian research ( indicates that a reduction of >50% can be achieved by an emissions based maintenance programme with increased productivity NIOSH (Mining) in the USA have also shown similar outcomes 22

23 Used a laboratory instrument mounted in a trailer to measure raw exhaust EC levels Demonstrated link between maintenance & raw exhaust DP reduction Demonstrated productivity gains of 5-7% from emission based monitoring programmes (based on increased available power). Similar or greater results overseas 23

24 Vehicle Pre Mtce. EC mg/m 3 Post Mtce. EC mg/m 3 Maintenance Performed PJB A New fuel pump and cleaned scrubber tank PJB B New scrubber tank, New injectors, adjusted fuel Ram Car Replaced injectors PJB C Replaced injectors, cleaned scrubber tank and intake air system

25 Airborne Concentrations: Method NIOSH 5040 Impactor with quartz filter Fits into a cyclone Flow Rate 2 L/min Current international standard Diesel particulate impactor cassette Source: SKC

26 Extensive research has shown elemental carbon to be a much easier surrogate for diesel particulate to sample & analyse that total carbon or other surrogates EC is easily detectable by thermal-optical methods (NIOSH Method 5040) EC is being used by regulatory authorities around the world as a analysis method when setting exposure limits

27 Raw exhaust concentrations: Numerous devices used to measure the amount of DP in the raw exhaust of engines Most are based on light scattering and suffer from optical interferences in many cases Independent calibration of all raw exhaust devices is a major issue Some devices show promise (MAHA MPM-4) but require specialist operators

28 Source: Coal Services

29 Freudenberg (Micro Fresh) have now formed a Joint Venture with SKC Inc for further development and IP sharing Prototype is being designed based on SKC s latest iteration of integrated hardware Freudenberg have partnered with market leading industrial design firm, Design & Industry for prototype development

30 Developing the ex-skc Diesel Detective technology: Handheld Basic operation designed for workshop use Robust Uses differential pressure through build-up of particulate on to a filter to indicate DP Cartridge type filter system

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34 Irrespective of calibration issues provided you use the same device and calibrate it the same way it can be used as an effective measurement tool (albeit not absolute) for the control of DP in raw exhaust Research at UoW to independently calibrate such devices should allow comparison of results from different technologies (expected to commence in 3 Qtr 2011) 34

35 Whole diesel exhaust remains listed as a probable human carcinogen by IARC (2A) It will be a considerable time before an absolute answer as to carcinogenic potency of DP is resolved (if ever) Statutory bodies around the world have reacted to IARC 2A listing. This is driving technology changes but may have created other problems 35

36 Non malignant health effects set to over shadow cancer risk as we move to new engine designs Controlling DP at the source has positive health effects & productivity gains Some mining companies have introduced an absolute requirement to control carcinogens (including DP) 36

37 Questions? 37