"Some experimental evidence and some epidemiologic evidence suggest that emissions from diesel-powered engines may be lung carcinogens, but the epidemiologic evidence is inconclusive." [Siemiatycki, p. 336] Assessment of risk is difficult because of improvements in diesel engines in recent years. [Schottenfeld, p. 364] IARC announced on June 12, 2012 that diesel exhaust had been reclassified as a Group 1 carcinogen and that the evidence was sufficient for lung cancer. [IARC Monographs, Volume 105] "Alternately, would the replacement of 'old' with 'new' technology diesel engines, which drastically reduce emissions of many compounds and elemental carbon, prove to be sufficient for safety from disease for the millions of diesel-exposed workers and the populations in urban areas worldwide? If so, improving air quality to protect health may depend to a large extent on the turnover rate from old- to new-technology engines in both developed and developing countries." [PMID 28069968
] "Diesel asthma" was documented in three railroad workers who developed reactive airway disease after heavy exposure to locomotive exhaust while riding behind the engine in caboose-less trains. [PMID 8433186
] Increased risk of COPD mortality was found in railroad workers exposed to diesel exhaust in the period 1960-1990; [Reference #2] Tunnel workers exposed to nitrogen dioxide from blasting and diesel exhaust had decreased pulmonary function. [PMID 14985522
] See "Diesel exhaust exposures in port workers." [PMID 26891343
] See "Nitrogen dioxide." See "1-Nitropyrene."