As New Delhi’s air quality level drops into the “poor” category again, with indications that it will get worse, the issue that returns to haunt the capital is that of stubble burning. Like Banquo’s Ghost in Shakespeare’s Macbeth, there is no mistaking it. According to news reports, images taken by US space agency Nasa show several farmland fires across northwest India. This is crop waste being burnt by farmers, and Delhi has already begun to choke.

The System of Air Quality Forecasting and Research has issued a health advisory asking people to reduce heavy exertion. Delhi’s Chief Minister Arvind Kejriwal has issued a statement asking residents to brace themselves for the haze ahead. An odd-even scheme for private vehicles is planned, too. But what needs to be addressed the problem of stubble fires.

Several states have banned it, but enforcement seems to be weak. In Haryana, for instance, reports say many farmers still consider it the best way to dispose of their crop refuse. Equipment is available for smokeless disposal, but these machines are proving too expensive for farmers—despite generous subsidy schemes. They can be taken on rent as well, but even the rental price has many of them grumbling. Some of them are debt ridden. Others are barely able to make ends meet on their produce. The smoke their traditional farm practices emit appear to be the last of their problems. Government intervention needs to sharpen. Else, it will be the same story year after year.