Volatile methyl siloxanes (VMS) are a group of organosilicon compounds of interest because of their potential health effects, their ability to form secondary organic aerosols, and their use as tracer compounds. VMS are emitted in the gas-phase from using consumer and personal care products, including deodorants, lotions, and hair conditioners. Because of this emission route, airborne concentrations are expected to increase with population density, although there are few studies in large urban centers. Here, we report summertime concentrations and daily variations of VMS congeners measured in New York City. Median concentrations of the 6 studied congeners, D3 (20 ng m^–3), D4 (57 ng m^–3), D5 (230 ng m^–3), D6 (11 ng m^–3), L5 (2.5 ng m^–3), and L7 (1.3 ng m^–3) are among the highest reported outdoor concentrations in the literature to date. Average congener ratios of D5:D4 and D5:D6 were consistent with previously reported emissions ratios, suggesting that concentrations were dominated by local emissions. Measured concentrations agree with previously published results from a Community Multiscale Air Quality model and support commonly accepted emissions rates for D4, D5, and D6 of 32.8, 135, and 6.1 mg per capita per day. Concentrations of D4, D5, D6, L5, and L7 and total VMS were significantly lower during the day than during the night, consistent with daytime oxidation reactivity. Concentrations of D3 did not show the same diurnal trend but exhibited a strong directional dependence, suggesting that it may be emitted by industrial point sources in the area rather than personal care product use. Concentrations of all congeners had large temporal variations but showed relatively weak relationships with wind speed, temperature, and mixing height.

中文翻译：

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纽约市挥发性甲基硅氧烷的浓度反映了个人护理和工业用途的排放


挥发性甲基硅氧烷 (VMS) 是一组令人感兴趣的有机硅化合物，因为它们具有潜在的健康影响、形成二次有机气溶胶的能力以及用作示踪化合物。使用消费品和个人护理产品（包括除臭剂、乳液和护发素）会以气相形式排放 VMS。由于这种排放途径，空气中的浓度预计会随着人口密度的增加而增加，尽管在大城市中心进行的研究很少。在这里，我们报告了在纽约市测量的 VMS 同系物的夏季浓度和每日变化。 6 个研究同源物的中位浓度，D3 (20 ng m ^–3 )、D4 (57 ng m ^–3 )、D5 (230 ng m ^–3 )， D6 (11 ng m ^–3 )、L5 (2.5 ng m ^–3 ) 和 L7 (1.3 ng m ^–3 ) 是报告的最高室外浓度之一。迄今为止的文献。 D5:D4 和 D5:D6 的平均同源物比率与之前报告的排放比率一致，表明浓度主要由当地排放量决定。测量的浓度与之前发布的社区多尺度空气质量模型结果一致，并支持普遍接受的 D4、D5 和 D6 排放率（人均每天 32.8、135 和 6.1 毫克）。白天 D4、D5、D6、L5 和 L7 以及总 VMS 的浓度显着低于夜间，这与白天的氧化反应性一致。 D3 的浓度没有表现出相同的昼夜趋势，但表现出强烈的方向依赖性，表明它可能是由该地区的工业点源排放的，而不是个人护理产品的使用。 所有同系物的浓度都有较大的时间变化，但与风速、温度和混合高度的关系相对较弱。