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Portable photocatalytic air cleaners were investigated in 24 and 48 m(3) emission test chambers with regard to efficiency and by-product generation. For this purpose, formaldehyde, decane, 1,2-dichlorobenzene, toluene, α-pinene and heptanal were doped at sub-ppm concentration levels into the chambers individually and in mixtures. By way of specified test protocols, efficiencies could be distinguished but were strongly dependant on the choice of test compounds, especially on whether single or multi compound dosing was used, and on long-term effects. Initial clean air delivery rates (CADRs) up to 137 m(3)/h were measured. Typical by-products were found in significant concentrations. The main ones were formaldehyde up to 50 ppb (62 μg/m(3)) and acetone up to 80 ppb (190 μg/m(3)). Other aldehydes were also found, but at smaller levels. The detection of chloroacetone, a strong irritating compound, at concentrations up to 15 ppb (57 μg/m(3)) strengthens the importance of such investigations especially in cases were chloro-organic compounds are involved.

Exploring the staggered short sale deregulation on the Chinese stock market as quasi-exogenous shocks, we find that the introduction of short selling is associated with higher deviations of labor investment from the level justified by economic fundamentals, i.e., lower labor investment efficiency. The main effect is more pronounced for firms that are more opaque, younger, and worse governed. Further evidence indicates that short sale deregulation mainly induces firms to overinvest in labor. Our overall findings suggest that faced with downward price pressures, firms may overinvest in labor to convey favorable information to stakeholders, resulting in less efficient labor investments.

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