Chemical modification of coating of Pinus halepensis pollen by ozone exposure.

Pollen coating, located on the exine, includes an extractible lipid fraction. The modification of the pollen coating by air pollutants may have implications on the interactions of pollen with plant stigmas and human cells. Pinus halepensis pollen was exposed to ozone in vitro and the pollen coating was extracted with organic solvent and analyzed by GC-MS. Ozone has induced chemical changes in the coating as observed with an increase in dicarboxylic acids, short-chain fatty acids and aldehydes. 4-Hydroxybenzaldehyde was identified as the main reaction product and its formation was shown to occur both on native pollen and on defatted pollen. 4-Hydroxybenzaldehyde is very likely formed via the ozonolysis of acid coumaric-like monomers constitutive of the sporopollenin. Modification of pollen coating by air pollutants should be accounted for in further studies on effect of pollution on germination and on allergenicity.

Data on comparison between FLEC and CLIMPAQ methods used for fast sorption measurements of VOCs on building materials.

A test emission chamber called CLIMPAQ has been coupled to a chromatography analyzer GC to measure volatile organic compounds (VOC) concentration during a sorption experiments (Fast sorption measurements of VOCs on building materials: Part 2 - Comparison between FLEC and CLIMPAQ methods, (Rizk et al., In press) [1]). The equations used to calculate the mass transfer coefficient and the thickness of the boundary layer developed on the surface of a material are presented. In addition, the experimental profiles obtained using the CLIMPAQ chamber is also presented in the presence and the absence of a building material. Finally, the impact of chamber size on the obtained concentration profile using different chambers is shown using 3 types of chambers having different volumes, 1 m(3), 30 m(3) and a micro chamber of 40 mL.

Reactive and nonreactive ozone uptake during aging of oleic acid particles.

The ozonolysis of submicrometer (150 nm) oleic acid (OL) particles in an aerosol flow tube has been studied for a wide range of initial ozone concentrations from 25 ppb to 1100 ppb. Both reactants were monitored, as well as the four main reaction products (nonanal, azelaic acid, nonanoic acid, and 9-oxononanoic), by gas chromatography-mass spectrometer, high resolution-time of flight-aerosol mass spectrometer, proton transfer reaction-time of flight-mass spectrometer, and ozone analyzer. The values for the initial uptake coefficients derived from each reactant decay are in the same range: γO3-0 = (1.5 ± 0.1) × 10(-3) and γOL-0 = (1.0 ± 0.2) × 10(-3). The ozone uptake coefficient is highly decreased when particles are in an advanced oxidized state (γO3-∞ = 5 × 10(-5)). Concerning reaction products, nonanal was mainly observed in the gas-phase (∼80%) with a carbon yield of ∼29%. Nonanoic, azelaic, and 9-oxonanonoic acids have been quantified in the condensed phase with carbon yields of respectively 6.6%, 5.3%, and 31.4%. The changes in chemical composition induce a slight rise in particle density, whereas the aerodynamic particle diameter increases by 10%. The initial molar quantities of ozone and OL were chosen to obtain different initial stoichiometries in order to explore conditions where either of them is the limiting reactant. Drastic changes in reactivity were observed as a function of the initial stoichiometry. In conditions where OL was the initial limiting reactant, up to a total of four molecules of O3 were lost from the gas phase, whereas only one OL molecule was consumed.