Development of an Advanced Retrofit Aftertreatment System Targeting Toxic Air Contaminants and Particulate Matter Emissions From HD-CNG Engines

Increasing urban pollution levels have led to the imposition of evermore stringent emissions regulations on heavy-duty engines used in transit buses. This has made compressed natural gas (CNG) a promising fuel for reducing emissions, particularly particulate matter (PM) from heavy-duty transit buses. Indeed, research studies performed at West Virginia University (WVU) and elsewhere have shown that pre-2010 compliant natural gas engines emit an order of magnitude lower PM emissions, on a mass basis, when compared to diesel engines without any exhaust aftertreatment devices. However, on a number basis, particle emissions in the nanoparticulate range were an order of magnitude higher for natural gas fueled buses than their diesel counterparts. There exists a significant number of pre-2007 CNG powered buses in transit agencies in the US and elsewhere in the world. Therefore, an exhaust aftertreatment device was designed and developed by WVU, in association with Lubrizol, to retrofit urban transit buses powered by MY2000 Cummins Westport C8.3G+ heavy-duty CNG engines, and effectively reduce Toxic Air Contaminants (TAC) and PM (mass and number count) exhaust emissions. The speciation results showed that the new exhaust aftertreatment device reduced emissions of metallic elements such as iron, zinc, nonmetallic minerals such as calcium, phosphorus and sulfur derived from lube oil additives to non-detectable levels, which otherwise could contribute to an increase in number count of nanoparticles. The carbonyl compounds were reduced effectively by the oxidation catalyst to levels below what were found in the dilution air. Also, hydrocarbons identified as TAC’s by California Air Resource Board (CARB) [1] were reduced to non-detectable levels. This ultimately reduced the number of nanoparticles to levels equal to that found in the dilution air.

Implications for Community Health from Exposure to Bushfire Air Toxics

Environmental Context. Significant bushfires have recently occurred in Indonesia (1997), Europe (2002), Australia (2000–2001) and the USA (2003), and burned large areas over extended periods of time. They cause widespread and serious air pollution through the release of respirable particles and other toxic air contaminants. These large fire events have shown clear impacts on community health and have caused increasing concern about the impact of bushfire smoke, whether from accidental or planned fires, on the health of surrounding communities. Abstract. Bushfires can cause widespread air pollution through the emission of high levels of toxic air contaminants that affect the health of surrounding communities. This review of studies that have evaluated the health impacts of bushfires in North America, Australia and South-East Asia shows that the primary pollutant consistently exceeding air quality guidelines is particulate matter. Elevated levels of respirable particles are likely to be the major cause of the higher number of hospital visits and admissions for respiratory and/or cardiovascular treatment, increased mortality, and elevated respiratory-related symptoms that were observed in communities after major bushfire events. Morbidity effects were found to be mostly short-lived and reversible after exposure ceased, and were more prevalent among susceptible groups such as asthmatics, children, the elderly, and people with pre-existing respiratory and/or cardiac illnesses. Implications of such exposures to the Australian population will be discussed in relation to existing (urban) air quality measures and options for community response to bushfire events.