Urban Air Pollution Levels Research Articles

Evaluation of air pollution phytotoxicity in a seasonally dry tropical urban environment

This study was conducted in the urban environment of Varanasi, India, to evaluate the plant responses to urban air pollution. Twenty sites were selected in four different zones of the city. At each site, seven woody perennials of same age classes were selected. Out of the four zones (I, II, III and IV), zone IV was used as a reference (control) zone as it received the minimum pollution input. Plant species growing in polluted and control areas were compared with respect to foliar dust load, per cent leaf area injury, leaf area, specific leaf weight and chlorophyll, ascorbic acid, SO 4 (2-) S and total N concentration in the leaves. Results indicated that the air pollution level in Varanasi causes leaf damage, reduces leaf area, specific leaf weight and chlorophyll, ascorbic acid and total N concentrations in the leaves. Sulphur concentration in leaves increased with increasing level of SO2 in the ambient air. The magnitude of such changes was maximum at the zone receiving maximum pollution load. Carissa carandas was found to be the most sensitive species and Bougainvillea spectabilis, the least. The study shows that the urban air pollution level in Varanasi is detrimental for the growth of plants involved in this study.

Quantitative Pathology of Nasal Passages in Rats Exposed to Urban Levels of Air Pollution

In order to assess the adverse effects of urban levels of air pollution, rats were used as biological indicators in a chronic exposure experiment. Animals were housed for 6 months in the center of São Paulo (the largest South American town) and compared to controls kept for the same period in a clean area. Pollution levels were obtained from a state air pollution monitoring station, 200 m distant from exposure location, which provided the levels of CO, SO 2, particulates, and ozone. The nasal septum was submitted to quantitative analysis of morphological and histochemical parameters, comprising the measurement of volume of epithelium and lamina propria per unity of surface of basal lamina, the amount of mucus stored in the surface epithelium, the volume densities of neutral and acidic mucus in the lamina propria glands, and the densities of secretory and ciliated cells in the epithelium. The results obtained in the present investigation suggest that chronic exposure to urban levels of air pollution induces secretory hypertrophy, combined with a shift toward acidic mucus secretion and ciliary damage. The results are consistent with the idea that prolonged exposure to low levels of air pollution deteriorates respiratory defenses against infectious agents and may cause an increase in respiratory morbidity and perhaps mortality.

Evaluation of air pollution phytotoxicity in a seasonally dry tropical urban environment using three woody perennials

SUMMARYA two‐year study was conducted in the urban environment of Varanasi, India, to evaluate plant responses to urban air pollution. Three species including a shrub (Carissa carandas L.) and two tree species (Delonix regia Rafin and Cassia fistula L.) were grown in pots at selected study sites. Changes in plant performance were considered in relation to the status of ambient air quality.Reductions in plant height, basal diameter, canopy area, plant biomass and chlorophyll, ascorbic acid and nitrogen contents in leaves were correlated with air pollution level at different sites. The magnitude of response indicated the relative sensitivity of the three species in the order D. regia > C. fistula > C. carandas. Shifts in relative contribution of photosynthate to leaf production and shoot growth appear to be a pollution‐induced adaptive response in C. carandas. The study shows that the urban air pollution level at Varanasi is detrimental to the growth of plants.

Respiratory alterations due to urban air pollution: An experimental study in rats

In order to assess the adverse effects of urban levels of air pollution, rats were used as biological indicators in a chronic exposure experiment. Animals were housed for 6 months in the center of São Paulo (the largest South American city) and were compared to controls kept for the same period in a clean area. Pollution levels were obtained from a State air pollution monitoring station, 200 m distant from the exposure place, which provided the levels of CO, SO2, particulates, and ozone. The animals were submitted to several tests focusing on the respiratory system, comprising pulmonary function tests, studies on mucociliary clearance and mucus rheology, histochemical evaluation of airways, bronchoalveolar lavage, and ultrastructural studies of the epithelium of the airways. Rats exposed to air pollution developed secretory cell hyperplasia in the airways, ultrastructural ciliary alterations, and a more rigid mucus, changes that caused mucociliary clearance impairment. In addition, nasal resistance and the number of inflammatory cells recovered by bronchoalveolar lavage were increased in air pollution exposed animals. The results obtained in the present investigation suggest that chronic exposure to urban levels of air pollution may cause respiratory lesions in rats.