Indoor measurements of the sum of the nitrate radical, NO3, and nitrogen pentoxide, N2O5 in Denmark.

There is a need for indoor measurements of nitrate radicals (NO(3)) and nitrogen pentoxide (N(2)O(5)) to better understand removal and transformation of volatile organic compounds in indoor environments, and to evaluate the possible health effects from exposure to nitrated reaction products. NO(3) and NO(2) react to form N(2)O(5) in the presence of a third molecule, and the fast equilibrium necessitates measurements of both NO(3) and N(2)O(5) in the evaluation of indoor NO(3) chemistry. The sum of these two species, NO(3)( *), was quantified in an office building in Denmark by measuring an oxidation product of the cyclohexene/NO(3) reaction in a flow-tube set-up. NO(3)( *) concentrations ranged from 1 to 58ppt, where N(2)O(5) was estimated to account for more than 68%. The concentrations of the precursors, NO(2) and O(3), and the photolysis of NO(3) were parameters, which clearly influenced NO(3)( *) apparent from the different precursor concentrations, lighting and daylight versus dark samples in this study. Also indoor air pollutants, in particular alkenes such as limonene and alpha-pinene, can significantly reduce NO(3)( *). These first indoor measurements of NO(3)( *), warrant further high time resolution measurements of NO(3), N(2)O(5), and organic nitrates indoors.

Secondary ozonides of substituted cyclohexenes: a new class of pollutants characterized by collision-induced dissociation mass spectrometry using negative chemical ionization.

Recent studies indicate that secondary ozonides of cyclic alkenes are formed in atmospheric reactions and may be relatively stable. The secondary ozonides (SOZs) of cyclohexene (1), 1-methylcyclohexene (2), 4-isopropyl-1-methylcyclohexene (3) and 4-isopropenyl-1-methylcyclohexene (limonene) (4) have been characterized by rapid gas chromatography electron ionization (EI), negative and positive chemical ionization (CI: ammonia, isobutane and methane) and collision-induced dissociation (CID) mass spectrometry. Both EI and positive CI spectra were found unsuitable for reproducible analysis. However, negative CI showed stable (M-H)(-) ions with minor fragmentation. CID of the (M-H)(-) ions resulted in simple and reproducible fragmentation patterns for all four SOZs with loss of m/z 18, 44 and 60, tentatively assigned as H(2)O, CO(2) and C(2)H(4)O(2) or CO(3), respectively. Thus, negative CI-MS-MS in combination with rapid gas chromatography is the preferred method for identification of secondary ozonides of cyclohexenes.

[Does the modern office environment desiccate the eyes?]. / Udtørrer det moderne kontormiljø øjnene?

Eye irritation is a common complaint in the modern office environment. The causes are still unknown. It appears that high preocular relative humidity protects the precorneal tear film against desiccation and airborne chemicals and reduces the development of eye irritation by airborne sensory irritants. This is particularly relevant for intensive computer work, where the precorneal tear film is altered, resulting in dryness of the eye. The reduction of the blink frequency during computer work promotes desiccation of the precorneal tear film; the frequency is moderately correlated with both the tear film thickness and the aqueous loss. For this reason, it is important to plan the workplace and work schedule in such a way to maintain a normal eye blink frequency to minimise alterations of the precorneal tear film.