5.1 The test method supports previously proposed occupational exposure standards (7, 8) for DPM. A DPM exposure limit has since been promulgated for metal and nonmetal mines, but there currently are no limits for general occupational settings (a proposed limit (7) was withdrawn from the ACGIH Notice of Intended Changes (NIC) list in 2003). In the United States alone, over a million workers are occupationally exposed (9). An exposure standard for mines is especially important because miners’ exposures are often quite high. NIOSH (9), the International Agency for Research on Cancer (10) (IARC), the World Health Organization (11) (WHO), the California Environmental Protection Agency (12), the U.S. Environmental Protection Agency (13) (EPA), and the National Toxicology Program (14) reviewed the animal and human evidence on DPM and all classified diesel exhaust as a probable human carcinogen or similar designation. In 2012, the WHO reclassified diesel exhaust as carcinogenic to humans (Group 1) (15). In addition, in a study of miners, the National Cancer Institute (NCI) and NIOSH reported increased risk of death from lung cancer in exposed workers (16 and 17).
5.2 The test method provides a measure of occupational exposure to DPM. Given the economic and public health impact of epidemiological studies, accurate risk assessment is critical. The NIOSH/NCI study of miners exposed to diesel exhaust provides quantitative estimates of lung cancer risk (16 and 17). The test method was used for exposure monitoring. Since publication (in 1996) as NMAM 5040, the method has been routinely used for occupational monitoring (5).
5.3 Studies indicate a positive association between airborne levels of fine particles and respiratory illness and mortality (18-26). The test method and others have been used for EPA air monitoring networks and air pollution studies. Because different methods produce different results, method standardization is essential for regulatory compliance determinations and valid comparisons of interlaboratory data.
5.4 The test method is being applied for emission-control testing.
1.1 This test method covers determination of organic and elemental carbon (OC and EC) in the particulate fraction of diesel engine exhaust, hereafter referred to as diesel particulate matter (DPM). Samples of workplace atmospheres are collected on quartz-fiber filters. The method also is suitable for other types of carbonaceous aerosols and has been widely applied to environmental monitoring. It is not appropriate for sampling volatile or semi-volatile components. These components require sorbents for efficient collection.