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A total of 13 diesel buses and 12 diesel trucks in Macao were tested using portable emission measurement systems (PEMS) including a SEMTECH-DS for gaseous emissions and a SEMTECH-PPMD for PM 2.5 . The average emission rates of gaseous pollutants and CO 2 are developed with the operating mode defined by the instantaneous vehicle specific power (VSP) and vehicle speed. Both distance-based and fuel mass-based emission factors for gaseous pollutants (e.g., CO, THC and NO X ) are further estimated under typical driving conditions. The average distance-based NO X emission of heavy-duty buses (HDBs) is higher than 13 g km −1 . Considering the unfavorable conditions for selective reductions catalyst (SCR) systems, such as low-speed driving conditions, more effective technology options (e.g., dedicated natural gas buses and electric buses) should be considered by policy makers in Macao. We identified strong effects of the vehicle size, engine displacement and driving conditions on real-world CO 2 emission factors and fuel consumption for diesel vehicles. Therefore, detailed profiles regarding vehicle specifications can reduce the uncertainty in their fleet-average on-road fuel consumption. In addition, strong correlations between relative emission factors and driving conditions indicated by the average speed of generated micro-trips are identified based on a micro-trip method. For example, distance-based emission factors of HDBs will increase by 39% for CO, 29% for THC, 43% for NO X and 26% for CO 2 when the average speed decreases from 30 km h −1 to 20 km h −1 . The mitigation of on-road emissions from diesel buses and trucks by improving traffic conditions through effective traffic and economic management measures is therefore required. This study demonstrates the important role of PEMS in understanding vehicle emissions and mitigation strategies from science to policy perspectives. [ABSTRACT FROM AUTHOR]

Abstract: The air quality impacts of aviation are becoming increasingly important given their impact on human health and the projected growth of aviation. In the United States, the government has set targets to manage and reduce the environmental impacts of aviation. In an environmental policy assessment context it is often necessary to rapidly evaluate many possible scenarios, and quantification of uncertainty is important. This makes direct application of comprehensive air quality models such as the Community Multiscale Air Quality (CMAQ) modeling system impractical due to computational cost. Here we develop a response surface model (RSM) – a form of rapid surrogate model – of the impact of aviation emissions on air quality in the United States. We develop an RSM design space and populate it with results from 46 CMAQ simulations, and perform cross-validation of the resultant RSM. The RSM models present-day as well as future impacts amid changing population and non-aviation emissions sources. This enables rapid estimates of the (particulate matter) air quality and human health impacts of aviation emissions scenarios. Cross-couplings between precursor gaseous emissions and PM2.5 species are found, consistent with competition for atmospheric ammonia. We apply the RSM to quantify the human health benefits of emissions reductions in 2018. Using the RSM we estimate that in 2005, aviation landing and takeoff emissions cause ∼195 [90% CI: 80–340] early deaths, while the same emissions cause ∼350 [90% CI: 145–610] mortalities in 2018. An emissions tradespace between aviation NO x and SO x emissions is constructed. It is found that with fleet-wide desulfurization of jet fuel, a 35% reduction in aviation NO x emissions would result in maintaining the same level of aviation-attributable early deaths in 2018 relative to 2005 levels, while an 80% reduction in NO x emissions would half aviation-attributable early deaths. [Copyright &y& Elsevier]

Abstract: The potential adverse human health impacts of emissions from UK airports have become a significant issue of public concern. We produce an inventory of UK airport emissions – including emissions from aircraft landing and takeoff operations, aircraft auxiliary power units (APUs) and ground support equipment (GSE) – with quantified uncertainty. Emissions due to more than 95% of UK passenger enplanements are accounted for. We apply a multi-scale air quality modelling approach to assess the air quality impacts of UK airports. Using a concentration-response function we estimate that 110 (90% CI: 72–160) early deaths occur in the UK each year (based on 2005 data) due to UK airport emissions. We estimate that up to 65% of the health impacts of UK airports could be mitigated by desulphurising jet fuel, electrifying GSE, avoiding use of APUs and use of single engine taxiing. Two plans for the expansion of UK airport capacity are examined – expansion of London Heathrow and new hub airport in the Thames Estuary. Even if capacity is constrained, we find that the health impacts of UK airports still increases by 170% in 2030 due to an increasing and aging population, increasing emissions, and a changing atmosphere. We estimate that if Heathrow were to be expanded as per previous UK Government plans, UK-wide health impacts in 2030 would increase by 4% relative to the 2030 constrained case, but this increase could become a 48% reduction if emissions mitigation measures were employed. We calculate that 24% of UK-wide aviation-attributable early deaths could be avoided in 2030 if Heathrow were replaced by a new airport in Thames Estuary because the location is downwind of London, where this reduction occurs notwithstanding the increase in aircraft emissions. A Thames hub airport would (isolated from knock-on effects at other airports) cause 60–70% fewer early deaths than an expanded Heathrow, or 55–63% fewer early deaths than an unexpanded Heathrow. Finally, replacing Heathrow by a Thames Estuary airport combined with emissions mitigation measures would reduce UK-wide aviation-attributable early deaths by 56% in 2030 while increasing aircraft movements, which would represent aviation causing about the same level of adverse health impacts as today in absolute terms. We note that because aviation emissions are included in the EU Emissions Trading Scheme, all options are CO2-neutral in terms of direct emissions (but not climate-neutral). [Copyright &y& Elsevier]