The prevalent theory in the pathogenesis of emphysema proposes that increased numbers of activated neutrophils and/or alveolar macrophages produce large amounts of proteases, an activity that cannot be regulated by alpha 1-antiproteases, resulting in lung destruction. However, the cells in the lung parenchyma of smokers have not been properly identified. We characterized and quantitated the inflammatory cell load in the lungs of smokers and correlated these findings with the degree of lung destruction. Twenty-one patients, six nonsmokers and 15 smokers, undergoing lung resection were studied. Lungs or lobes were fixed and stained for light microscopy and neutrophil identification and immunohistochemically stained for identification of lymphocytes and macrophages. By point counting, we determined the extent of emphysema by the volume density of the lung parenchyma (Vvalv), and the different cell numbers per cubic millimeter in all lungs. In nonsmokers Vvalv was greater than in smokers. The number of neutrophils/mm3 of lung correlated directly with the Vvalv, (r = 0.71, p < 0.01), whereas the number of alveolar macrophages (r = -0.70) and T-lymphocytes (r = -0.78) correlated negatively with the Vvalv. The number of T-lymphocytes correlated negatively with the number of neutrophils (r = -0.58) and positively with the numbers of alveolar macrophages (r = 0.77). Our data suggest that as long as the inflammatory reaction is predominantly of neutrophils there is no destruction of the lung. However, the extent of lung destruction becomes evident, and its extent is directly related to the number of alveolar macrophages and T-lymphocytes/mm3. We conclude that the T-lymphocyte might be importantly implicated in the pathogenesis of emphysema in smokers.

Smoke particles from biomass burning can generate forcing of climate by modifying cloud microphysics and reflectance of sunlight. Cloud modification, critical to an understanding of climate change, is uncertain and variable. Satellite data over the Amazon Basin and Cerrado were analyzed for cloud reflectance and droplet size and for smoke concentration. Smoke increased cloud reflectance from 0.35 to 0.45, while reducing droplet size from 14 to 9 micrometers. The regional variability of the smoke effect was correlated to the availability of water vapor. During the 3 months of biomass burning in the dry season, the smoke-cloud forcing of climate was only -2 watts per square meter in this region, much smaller than what can be inferred from model predictions.C l o u d modification by aerosol particles (1, 2) may be the missing process in reconciling climate models with observations (3). Yet the chemical and ohvsical Drocesses in-. , volved may be too complex for parameterization in climate models (4), and some generalization is needed. Large-scale observations of the relation between cloud properties, the surrounding aerosol, and meteorological parameters represent one way to achieve a quantification of the aerosol impact on cloud radiative properties and climate forcing. W e report observations that confirm the effect of aerosol ~articles on cloud mlcr'ophysical and radiaiive properties and quantify the dependence of this effect on the availability of total precipitable water vapor. The results, if not disproved in other cases, may form the basis for understanding the aerosol-cloud interaction as a first steo for use in climate models.Smoke aerosol particles generated from biomass-burning fires in the tropics (5) can affect atmospheric radiation (6) and climate directly by reflecting sunlight back to space (3). This effect was shown recentlv to be ~, relatively small (7). Aerosol can alio force climate indirectly by modifying cloud microphysics and reflectivity (2, 8). Smoke particles generated by fires and modified in the lower troposphere (9, 10) are effective cloud condensation nuclei (CCN) (1 1 ) and have been shown to increase the concentration of cloud droplets (1 1-13). Here we show that smoke particles also increase the reflectance of thin or moderately thick clouds.Measurements by satellite sensors, like the Advanced Very High Resolution Radiometer (AVHRR), allow derivation of cloud droolet size and reflectance and of the smoke optical thickness ( a measure of smoke concentration) in cloud-free regions (13). T h e relation between the cloud properties and the optical thickness of the aerosol can then be used to quantify smoke-cloud interaction. But measurements of this interaction from satellites may be complicated by the variability of the smoke particle size distribution, its hygroscopicity, and the presence of absorbing black carbon and cloud dynamics (4). Optical thickness is sensitive not only to the smoke concentration but also to the aerosol particle size. Large variability in the aerosol particle si...

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Fraser, R. S.; Nakajima, T.; Mattoo, S.; and Holben, B. N., "Size distribution and scattering phase function of aerosol particles retrieved from sky brightness measurements" (1994). Papers in Natural Resources. 271. https://digitalcommons.unl.edu/natrespapers/271

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