DPM Hazard ACGIH: 0.15 mg/m3, A2 (suspected human carcinogen) (1995); 0.05 mg/m3, A2 (1999); 0.05 mg/m3, A2 (2000); 0.02 mg/m3, (elemental carbon), A2 (2001); 0.02 mg/m3, A2 (2002); Withdrawn (2003); ACGIH- TLV for DPM –Under Notice of Intended Change (NIC) January 19, 2001- MSHA (USA) Risk Assessment with respect to health effects, was: “Exposure to DPM can materially impair miner health or functional capacity. These material impairments include acute sensory irritations and respiratory symptoms (including allergenic responses); premature death from cardiovascular, cardiopulmonary, or respiratory cause; and lung cancer.” 66 Fed. Reg. 5853-5855 (Jan. 19, 2001). MSHA-2001--Mean concentration of 0.64 mg/m3 TC for a period of 45 years of occupational exposure results in a relative risk of lung cancer of 2.0. This established an interim concentration limit of 400 ug/m3 using total carbon (TC) as a surrogate for DPM, and a final limit of 160 ug/m3 TC, which was to take effect on January 6, 2006. January 19, 2001-July 2005— 31 American Mines Study. July 6, 2005- 400 ug/m3 TC; 308 ug/m3 EC (TC/EC Ratio of 1.3 for 90% of the valid samples~ 464) January 20, 2007--the DPM limit was reduced to 350TC μg/m3 or 270EC μg/m3 May 20, 2008 –the final limit of 160TC μg/m3 and 123 ug/m3 EC
Diesel Engines in SA Mines Battery LocomotiveRusten Hornby Diesel Locomotive 1928- Van Dyk Consolidated Mines Ltd, Witwatersrand Mining regulations-Proportion of CO and CO2 should not be more than 0.01% and 0.2% respectively Dilution Factors varied from -0.013 m3/s/kw to 0.0325 m3/s/kW
Personal DPM Sampling Send DPM Filter Cassette For Analysis- NIOSH 5040 Analyzes Sample Filter For Total Carbon- OC-EC Control Filter Analyzed for the same
Engineering Sampling Pressure Differential over a DPM selective filter (metering pump) Robust Tested in South Africa for Respirable Dust Measurement-Health 704 Calibration Issues Overcome Production 6/08 Release (Nevada) 9/08 Diesel Detective (SKC / NIOSH)
DPM OEL History Coal Mining– No personal Exposure standard yet; RAW Exhaust Standard -2.5 grams/hr-Maximum emission per engine Australia—100 microgram/m3 (EC) or 200 microgram/m3 as TC (TC/EC Ratio-2) Germany (non-coal)-0.3 mg/m3 elemental carbon Canada Majority of Provinces 1.5 mg/m3 (RCD) Quebec0.6 mg/m3 (RCD) Ontario0.4 - 0.6 mg/m3 (?)
Calculations Where: DPM ST =sample DPM concentration measured in μg/m3 M=DPM mass (EC or OC) in μg/cm2 B=Controlled filter mass (EC or OC) in μg/cm2 FL=sample flow rate in liters per min ST=sampling time in min A=DPM filter deposition area, cm2 DPM Filter Deposition Areas NIOSH 5040 method-8.55 cm2 for a 37-mm filter when using a three piece style cassette. SKC impactor- between 8.11 and 8.21 cm2. MSHA-8.04 cm2. SA--??Like to Know
Calculation Errors Statistically significant differences More pronounced at stringent OELs Paired T-Test and CI: 8.04 cm2 Vs 8.40 cm2 Paired T N Mean StDev SE Mean 8.04 cm2 48 238.5 368.3 53.2 C11 48 249.2 384.8 55.5 Difference 48 -10.69 16.51 2.38 95% CI for mean difference: (-15.49, -5.90) T-Test of mean difference = 0 (vs not = 0): T-Value = -4.49 P-Value = 0.000
Adoption--Compliance Check OEL x Error Factor = Enforceable Limit Error factor for EC + OC = TC is 1.14; Error factor for EC x 1.3 = TC is 1.12 Enforceable DPM limit for EC + OC = TC is: 160 TC µg/m3 x 1.14 = 182.4 TC µg/m3 Enforceable DPM limit for EC x 1.3 = TC is: 123EC µg/m3 x 1.12 = 138TC µg/m3 Citable—Both TC values exceed their respective enforceable limit EC + OC = TC EC x 1.3 = TC 123 EC µg/m3 x 1.3 = 160TC µg/m3 123EC µg/m3 x 2.5 = 308TC µg/m3
Compliance Status?? January 6, 2003—19.3 % of mines non- compliance at 400 ug/m3 TC; Mean– 236 ug/m3 TC. 2007- USA--average exposure level was 181 µg/m3 TC and 21 % of the mines were cited for noncompliance. At the proposed limit of 160 µg/m3 TC, would they be out-of compliance-- ???!! South Africa-- ??
Way Forward Pro-actively carry out personal DPM exposure to understand the risk The adoption of overseas TC/EC ratio/limits for compliance needs to be scientifically determined. The ventilation planning and audit tool can be used effectively in all mines with regard to the number of diesel vehicles in use. Consider diesel engine database for engineering control solutions where applicable when carrying out Personal DPM exposure levels. DPM Measurement must be carried out in conjunction with the ventilation engineering parameters (m/s, m2, m3/s, WBT, DBT, humidity levels, Depth, BP)
Q & A Should the ventilation engineering department to know the sulphur content of the Sulphur Levels??-Yes Is “Tailpipe” Emissions Testing Required At Mine Site?-- No. This Is Engine Manufacturer’s Responsibility (MSHA, 2003). Should the ventilation engineering department sensitise this hazard with relevant people for risk assessment??- Yes Sharing of DPM information between the mines in order to arrive at an informed OEL for South Africa? --Yes
Way Forward …an input to scientific approaches in developing appropriate conversion factors and OELs (Step down approach) for DPM and also in ensuring appropriate error factors for compliance determination in SA.