Two-stroke scooters are a dominant source of air pollution in many cities.

Fossil fuel-powered vehicles emit significant particulate matter, for example, black carbon and primary organic aerosol, and produce secondary organic aerosol. Here we quantify secondary organic aerosol production from two-stroke scooters. Cars and trucks, particularly diesel vehicles, are thought to be the main vehicular pollution sources. This needs re-thinking, as we show that elevated particulate matter levels can be a consequence of 'asymmetric pollution' from two-stroke scooters, vehicles that constitute a small fraction of the fleet, but can dominate urban vehicular pollution through organic aerosol and aromatic emission factors up to thousands of times higher than from other vehicle classes. Further, we demonstrate that oxidation processes producing secondary organic aerosol from vehicle exhaust also form potentially toxic 'reactive oxygen species'.This work was supported by the Swiss Federal Office for the Environment (FOEN), the Federal Roads Office (FEDRO), the Swiss National Science Foundation (Ambizione PZ00P2_131673, SAPMAV 200021_13016), the EU commission (FP7, COFUND: PSI-Fellow, grant agreement n.° 290605), the UK Natural Environment Research Council (NERC), the French Environment and Energy Management Agency (ADEME, Grant number 1162C00O2) and the Velux Foundation.This is the accepted manuscript version. The final version is available from http://www.nature.com/ncomms/2014/140513/ncomms4749/full/ncomms4749.html

A Survey on the Quality Information Provided by

The last decade marked the first real attempt to turn software development into engineering through the concepts of ComponentBased Software Development (CBSD) and Commercial Off-The-Shelf (COTS) components. The idea is to create high-quality parts and join them together to form a functioning system. One of the most critical processes in CBSD is the selection of the COTS components from a repository that meet the user requirements. Current approaches try to propose appropriate quality models for the effective assessment of such components. These proposals define quality characteristics, attributes, and metrics, which are specific to the particular nature of COTS components and CBSD. However, we have found that the information required evaluating those components using those quality models and metrics is not usually available in the existing commercial software repositories. This paper presents a survey we have conducted on the most popular COTS component vendor sites, trying to evaluate how much of the information required to assess COTS components is actually available. Our goal was to estimate the current gap between the "required" and the "provided" information, since there is no point in defining theoretical measures for COTS components if the data they rest upon is not available. Analyzing this gap is the first step towards successfully bridging it, by both refining the component quality models so their metrics are more realistic, and by improving the information currently provided by software component vendors