 Not included in the official fatalities number were deaths that were recorded as pneumonia . Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning , brought on by the use of gasoline @-@ fueled vehicles in the diversion tunnels , and a classification used by Six Companies to avoid paying compensation claims . The site 's diversion tunnels frequently reached 140 ° F ( 60 ° C ) , enveloped in thick plumes of vehicle exhaust gases . A total of 42 workers were recorded as having died from pneumonia ; none were listed as having died from carbon monoxide poisoning . No deaths of non @-@ workers from pneumonia were recorded in Boulder City during the construction period . 
 Not included in <a href='None' title='1'><mark>the</mark></a>official fatalities <a href='negative_concord' title='2'><mark>number</mark></a> <a href='uninflect' title='3'><mark>were</mark></a> deaths <a href='null_relcl' title='4'><mark>that</mark></a><a href='uninflect' title='5'><mark>were</mark></a> recorded as pneumonia . Workers alleged that this diagnosis was a cover for death from carbon monoxide poisoning , brought on by the use of gasoline @-@ fueled vehicles in the diversion tunnels , and a classification used by Six Companies to avoid paying compensation claims . The site <a href='null_genetive' title='6'><mark>'s</mark></a>diversion tunnels frequently reached 140 ° F ( 60 ° C ) , enveloped in thick plumes of vehicle exhaust gases . A total of 42 workers <a href='uninflect' title='7'><mark>were</mark></a> recorded as <a href='been_done' title='8'><mark>having</mark></a> died from pneumonia ; <a href='None' title='9'><mark>none</mark></a> <a href='uninflect' title='10'><mark>were</mark></a> listed as <a href='been_done' title='11'><mark>having</mark></a> died from carbon monoxide poisoning . No deaths of non @-@ workers from pneumonia <a href='uninflect' title='12'><mark>were</mark></a> recorded in Boulder City during the construction period . 
Not included in official fatalities no number was deaths was recorded as pneumonia . Workers alleged dat this diagnosis was a cover for death from carbon monoxide poisoning , brought on by the use of gasoline @-@ fueled vehicles in da diversion tunnels , and a classification used by Six Companies to avoid paying compensation claims . Tdasite  diversion tunnels frequently reached 140 ° F ( 60 ° C ) , enveloped in thick plumes of vehicle exhaust gases . A total of 42 workers was recorded as done died from pneumonia ; don't none was listed as done died from carbon monoxide poisoning . No deaths of non @-@ workers from pneumonia was recorded in Boulder City during the construction period .