| 1. |
- Sandstrom, T, et al.
(författare)
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Inflammatory cell response in bronchoalveolar lavage fluid after nitrogen dioxide exposure of healthy subjects: a dose-response study
- 1991
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Ingår i: European Respiratory Journal. - 1399-3003. ; 4:3, s. 332-339
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Tidskriftsartikel (refereegranskat)abstract
- The combination of environmental chamber exposure and bronchoalveolar lavage (BAL) was used to study the effects of the common air pollutant nitrogen dioxide (NO2). Eighteen healthy nonsmokers were exposed to NO2 during 20 min in an exposure chamber during light bicycle ergometer work. All subjects were examined with BAL at least 3 wks before exposure, as a reference. The subjects were re-examined with BAL, in groups of eight, 24 h after exposure to 4, 7 and 10 mg NO2.m.3 (2.25, 4.0 and 5.5 ppm), respectively. An inflammatory cell response was found after exposure to all concentrations. An increase in the number of lymphocytes in BAL fluid was observed after 7 and 10 mg.m.3 (p less than 0.05 and 0.02, respectively). An increase in the number of mast cells, that appears to be dose-dependent, was found after exposure to all concentrations. The proportion of lysozyme positive alveolar macrophages was elevated after exposure to 7 mg.m.3. The inflammatory mediators fibronectin, hyaluronan, angiotensin converting enzyme (ACE) and beta 2-microglobulin were unchanged by exposure. Due to the findings of inflammatory cell changes far below the peak exposure limits for work places in industrialized countries, 9-18 mg.m.3, the safety of these limits is questioned. Studies are in progress in our laboratory using BAL to evaluate the effects of repeated NO2 exposure.
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| 2. |
- Bjornbom, E., et al.
(författare)
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Reduction of NOx with NH3 in presence of pyrolysed macro-cycle catalyst
- 1991
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Reduction of NOx with NH3 in the presence of pyrolyzed cobalt-tetraphenylporphyrin, CoTPP 'macro-cycle black', was studied. Active carbon, Norit RBXS 1, was used as a carrier. The experimental conditions were varied as follows: temperature from 95 to 140°C, space velocity of the gas mixture 1000-5000 h-1 and catalyst content 0-1%. The results showed that, in the experimental range studied, the temperature has no significant effect on the conversion of NOx. The conversion of NOx at low space velocity of the gas (1000 h-1) was high (approx. 90%), both in the presence and absence of CoTPP black. This was explained by the fact that the active carbon used as a catalyst support also has a catalytic effect on the reduction of NOx. At low space velocity this effect is sufficient to achieve high conversion of NOx in the presence of active carbon only. The conversion decreased at higher space velocity, however. The presence of CoTPP black counteracted the negative effect of the increased space velocity. The effect of the 'macro-cycle black' on the conversion of NOx was significant at higher space velocitites.
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