Monitoring of auto exhaust pollution by roadside plants.

The changing levels of SO2 and Pb in the air and vegetation, along ten road transections of Lucknow city (having varying traffic densities) have been investigated, with a view to authenticate a possible correlation between SO2 and Pb concentration in air and sulphate and lead accumulation in the foliage of avenue trees. The study showed that the road transection at Alambagh (traffic density 4835 for 2 h) revealed the highest level of pollutants (SO2, 202 µg m(-3); SPM, 1080 µg m(-3); and lead, 2.96 µg m(-3), 2 h average) in air, as well as in the foliage of plants, whereas the road stretches with less traffic density correspondingly showed lower levels of pollutants. Pb and sulphate in leaves were found to be positively correlated with Pb and SO2 pollution in the air. Results suggest that Dalbergia sissoo and Calotropis procera are the ideal plant species to monitor as indications of Pb and SO2, respectively, in the air.