“…The key emissions of concern are: oxides of nitrogen (NO x ) [104-107], particulate matter (PM or soot) [108][109][110], unburned hydrocarbons (UHC) [105,111,112] or oxygenates such as aldehydes [3,22,86,113], and carbon monoxide (CO) [3,105,113,114]. Nitrogen dioxide readily forms from nitric oxide in the atmosphere and causes respiratory problems, can react with ammonia and moisture to create small particles that can cause or aggravate respiratory disease and heart disease, and can react with volatile organic compounds (VOCs), such as UHCs, to form ground-level ozone [104].…”