Last week, we ruffled a feather or two by proposing a solution for our nation's congested streets: eliminating delivery trucks. With that idea (sort of) in mind, we turn our attention toward Calcutta, India, where six days ago, the city implemented a ban on 15-year-old (or older) commercial vehicles. In this case, they weren't attempting to alleviate congestion per se; the goal was to improve air quality by reducing particulate matter, which older vehicles spew out in great volume. According the BBC, it's already working.A survey done by the Calcutta-based Saviour and Friend of Environment (Safe) says that around the city's four most polluted intersections-the Dunlop crossing, the Shyambazar five-point crossing, Park Circus and the Rashbehari Avenue-SP Mukherjee Road crossing-hydrocarbon levels more than halved. That is important because high hydrocarbon levels have been blamed for an increase in liver and kidney illnesses as well as higher level of cancer. With less traffic on the roads, the oxygen count shot up by around 15 to 20 %, leading to a drop in the percentages of carbon dioxide and carbon monoxide. Suspended particulate matter, the main cause of bronchial diseases that makes Calcutta the asthma capital of India, dropped by 50%.The vehicles that have been removed from the road are pre-1993 buses (4,000), taxis (6,800), and auto-rickshaws (nearly all the city's 65,000). That removal, as you might imagine, hasn't exactly done wonders for keeping the city moving this past week. Nor has it done wonders for the workers whose (now nonexistent) jobs depended on the older, polluting vehicles; some displaced workers have tried to obstruct the operation of the city's new environmentally friendly vehicles.That all too common consequence of integrating much-needed environmental considerations into an industry-see reactions from mountain top removal workers, members of the shipping industry, farmers, etc.-leaves us with an often asked but rarely answered question: How do we clean up our industries without eradicating jobs? Is it worth it to improve the living (and, in this case, the breathing) conditions of millions of people if that means choking the financial throats of a few thousand people?Photo (cc) by Flickr user icultist. Via Treehugger.