NEW DELHI — When an acrid blanket of gray smog settled over India’s capital last month, environmentalists warned of health hazards, India’s Supreme Court promised action, and state officials struggled to understand why the air had suddenly gone so bad.
The heavy smog has dissipated for the moment, but it has left behind a troubling reality for one of India’s most important cities: Despite measures to improve air quality, pollution is steadily worsening.
‘‘This is like a ding-dong battle,’’ said Sheila Dikshit, the chief minister of the State of Delhi, moving her fingers like the flippers of a pinball machine. ‘‘We catch up with something; the pressures catch up more than that.’’
New Delhi, a growing metropolis of nearly 20 million people, has struggled to reconcile its rapid economic growth with environmental safeguards. Over a decade ago, the city introduced policies that raised emission standards, closed polluting industries, and expanded green spaces. Air quality visibly improved.
But those gains have been overwhelmed in recent years. ‘‘We have already plucked the low-hanging fruits, so to speak,’’ said Anumita Roychowdhury, the executive director of the Center for Science and Environment.
Environmentalists recommend a hefty tax on diesel vehicles, a steep increase in parking charges, and a rapid upgrade of the public trans-portation system.
But government officials say that a mere crackdown on vehicles ignores other aspects of of the problem. They note that New Delhi is landlocked and lacks the coastal breezes that flush polluted air out of other major Indian cities such as Mumbai and Chennai.
Weather conditions played a role, environmentalists agree, but that is no excuse for ignoring the underlying problems.
‘‘The government cannot say that the smog was solely because of bad weather,’’ said Mukesh Khare, a professor of environmental engineering at the Indian Institute of Technology in Delhi.