The Air Resources Board proposed to amend Cal. Code Regs. tit. 13 §1956.8, pertaining to heavy-duty diesel engine test procedures. Changes would modify the measurement allowance for the regulated particulate matter emissions during heavy-duty diesel in-use compliance testing when using portable emissions measurement systems. There will be a public hearing on June 23, 2011. http://www.oal.ca.gov/res/docs/pdf/notice/18z-2011.pdf pp.735-39.