National Institute for Occupational Safety and Health

“ Total carbon (as OC and EC) is determined by the method, but EC was recommended as a measure of workplace exposure because OC interferences may be present [2, 3] . Cigarette smoke and carbonates ordinarily do not interfere in the EC determination. Less than 1% of the carbon in cigarette smoke is elemental. If heavy loadings of carbonate are anticipated, a size-selective sampler (impactor and/or cyclone) should be used [2] . For measurement of diesel-source EC in coal mines, a cyclone and impactor with a submicrometer cutpoint are required to minimize collection of coal dust. ”

“ Sample at an accurately known flow rate. Typical rates are 2-4 L/min (note: Lower flows (e.g., 1 L/min) have been used in mines to prevent overloading) . 4. After sampling, replace top piece of cassette, if removed, and pack securely for shipment to laboratory. NOTE: Diesel particulate samples from occupational settings generally do not require refrigerated shipment unless there is potential for exposure to elevated temperatures (that is, well above collection temperature) . Filter samples normally are stable under laboratory conditions. ”

“ Analyze at least one replicate sample. For sets of up to 50 samples, replicate 10% of the samples. For sets over 50 samples, replicate 5% of the samples. If a filter deposit appears uneven (this should not be the case if the cassette is sealed properly) , take a second portion (step 5) for analysis to check evenness of deposition. NOTE: Precision of replicate analyses of a filter is usually better than 5% (1 to 3% is typical) .
NIOSH Manual of Analytical Methods (NMAM) , Fourth Edition ELEMENTAL CARBON (DIESEL PARTICULATE) : METHOD 5040, Issue 3, dated 15 March 2003 - Page 4 of 5 7. ”