Environmental pollution
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Environmental pollution · Nov 2016
PM2.5 pollution is substantially affected by ammonia emissions in China.
Urban air quality in China has been declining substantially in recent years due to severe haze episodes. The reduction of sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions since 2013 does not yet appear to yield substantial benefits for haze mitigation. As the reductions of those key precursors to secondary aerosol formation appears not to sufficient, other crucial factors need to be considered for the design of effective air pollution control strategies. ⋯ We highlight that more efforts should be directed to the reduction of NH3 emissions that help mitigate PM2.5 pollution more efficiently than other PM2.5 precursors. Such efforts will yield substantial co-benefits by improving nitrogen use efficiency in farming systems. As a consequence, such integrated strategies would not only improve urban air quality, but also contribute to China's food-security goals, prevent further biodiversity loss, reduce greenhouse gas emissions and lead to economic savings.
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Environmental pollution · Jan 2016
Origin of inorganic and organic components of PM2.5 in subway stations of Barcelona, Spain.
The present work assesses indoor air quality in stations of the Barcelona subway system. PM2.5 concentrations on the platforms of 4 subway stations were measured during two different seasons and the chemical composition was determined. A Positive Matrix Factorization analysis was performed to identify and quantify the contributions of major PM2.5 sources in the subway stations. ⋯ Subway PM2.5 source comprised emissions from rails, wheels, catenaries, brake pads and pantographs. The subway source showed different chemical profiles for each station, but was always dominated by Fe. Control actions on the source are important for the achievement of better air quality in the subway environment.
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Environmental pollution · Sep 2014
Ozone levels in European and USA cities are increasing more than at rural sites, while peak values are decreasing.
Ground-level ozone (O3) levels are usually lower in urban centers than nearby rural sites. To compare trends in O3 levels during the period 1990-2010, we obtained monitoring data from paired urban and rural sites from the European Environment Agency and the US Environmental Protection Agency. ⋯ The overall trend was for convergence between urban and rural O3 data. Ozone levels exceeded the criteria established for the protection of human and vegetation health at both urban and rural sites.
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Environmental pollution · Jan 2014
Influential parameters on particle concentration and size distribution in the mainstream of e-cigarettes.
Electronic cigarette-generated mainstream aerosols were characterized in terms of particle number concentrations and size distributions through a Condensation Particle Counter and a Fast Mobility Particle Sizer spectrometer, respectively. A thermodilution system was also used to properly sample and dilute the mainstream aerosol. Different types of electronic cigarettes, liquid flavors, liquid nicotine contents, as well as different puffing times were tested. ⋯ The total particle number concentration peak (for 2-s puff), averaged across the different electronic cigarette types and liquids, was measured equal to 4.39 ± 0.42 × 10(9) part. cm(-3), then comparable to the conventional cigarette one (3.14 ± 0.61 × 10(9) part. cm(-3)). Puffing times and nicotine contents were found to influence the particle concentration, whereas no significant differences were recognized in terms of flavors and types of cigarettes used. Particle number distribution modes of the electronic cigarette-generated aerosol were in the 120-165 nm range, then similar to the conventional cigarette one.
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Environmental pollution · Nov 2013
Have the short-term mortality effects of particulate matter air pollution changed in Australia over the period 1993-2007?
The author investigates whether the mortality effect of particulate matter air pollution (PM10) has changed in Australia over the period 1993-2007. This period corresponds to an era of increasing Government intervention aimed at improving air quality and, as a result, a potential decrease in the toxicity of PM10. Evidence is found that the mortality effect of PM10 has declined in both Brisbane and Sydney. ⋯ We speculate that one possible reason for this decline could be a reduction in the toxicity of PM10. A difference between this study and a similar United States study is that PM10 concentrations have not been declining in Australia. This means that the observed decline in the mortality effect of PM10 is not an artefact of a declining PM10 concentration.