A slight difference in the size ranges of measured UFPs due to the use of different instruments has a great impact on the measured overall PNC because the number concentration of particles increases remarkably in the smallest size fractions.
The objective of this study was to investigate the associations of size-specific PNC as well as lung-deposited PSC on natural, cardiovascular, and respiratory mortality in the Ruhr Area, based on a time-series study from March 2009 to December 2014.
Measured particle characteristics included size-specific PNC of ultrafine, fine, and coarse particles (as well as their PSC) that deposit in the alveolar or tracheobronchial region of the lung (short: lung-deposited PSC).
We chose single-lag models as well as aggregated 2- to 4-d lags over distributed lag-models because of multiple missing data in the PNC series and the respective loss of power, especially in the underlying small study population.
The main exposure metrics of interest were size-specific PNC, aggregated as ultrafine ([PNC.sub.<100]) and fine particles ([PNC.sub.100-750]), as well as PSC and [PM.sub.10].
The workshop provided basic information on PNC
thermodynamics and rheology, on their compounding, processing, and characterization.
Therefore, we calculated daily mean PNCs for particles categorized according to multiple size fractions, specifically, [PNC.sub.0.25-0.28], [PNC.sub.0.28-0.30], [PNC.sub.0.30-0.35], [PNC.sub.0.35-0.40], [PNC.sub.0.40-0.45], [PNC.sub.0.45-0.50], [PNC.sub.0.50-0.65], [PNC.sub.0.65-1.0], [PNC.sub.1.0-2.5], and [PNC.sub.2.5-10].
We used a time-series design to investigate the short-term effects of size-fractioned PNCs on daily mortality (Zeger et al.
Consistent with previous studies, we used 2-day moving average PNCs for the current and previous day (lag 01) in our main analyses (Chen et al.
The results are presented as mean percent changes in daily mortality [with 95% confidence intervals (CIs)] associated with an interquartile range (IQR) increase in size-fractionated PNCs. For seasonal analyses, exposure contrasts were scaled to IQRs for season-specific exposure distributions.
Generally, PNCs for particles [less than or equal to] 2.5 [micro]m in diameter were strongly correlated with mass concentrations of [PM.sub.2.5], and moderately correlated with mass concentrations of [PM.sub.10], [PM.sub.2.5-10], S[O.sub.2], and N[O.sub.2] (Table 2).
Considering that nanocomposites offer significant improvement of polymer performance, it is a historical necessity that PNCs
will progressively replace neat resins in their direct use as well as in composites, blends or foams.