2007, 2010 emission compliance vs OSHA compliance

[cartman]

Do 2007 and 2010 EPA emission compliant engines also meet OSHA indoor air quality compliance? There times the trucks have to run inside the building for a period time. Thank you for any help you can offer.

[wam]

Not from the regulatory point of view. The metrics of the EPA and OSHA regulations are totally different. OSHA sets exposure limits in the ambient air. The ambient concentrations of gases depend on ventilation in the building and on the tailpipe concentrations at a given engine operating condition (I suppose it's idle or low load while in the building) which are not known from the EPA certification data.

You could speculate that CO concentrations should be lower in 2007/2010 engines compared to 2004 and earlier engines. I think it's possible that the tailpipe CO is actually below the ambient OSHA limit, especially if the catalyst is still warm from driving (as opposed to cold start).

The bad news may be NO2. Due to the large catalyst volume, NO is oxidized to NO2 in engines with emission aftertreatment. NO2 emissions from 2007 engines are two to eight times higher than in 2004 engines (see ACES study). As long as the catalyst is still warm, high NO2 levels could occur even at idle/low load. Considering the low NO2 exposure limits by OSHA, this could put you out of compliance.

2010 engines have NOx reduction catalysts (SCR) which reduce NO2 to low levels when the engine operates at medium to high load. Idle NO2 levels would depend on the engine-out emissions, catalyst temperature and other factors. I'm not sure if idle/low load NO2 in 2010 engines would be lower or higher compared to 2004 engines.