Another Diwali has come and gone, accompanied by fire-crackers producing more smoke than light, leaving the faintly acrid smell of Delhi’s immensely polluted air. We don’t know quite how bad things were on Diwali, because air pollution levels were quite literally off the charts — too high to measure — for many monitoring stations.

Nevertheless, we can be certain that the Central Pollution Control Board’s (CPCB) newly developed air quality index (AQI) would have been glowing an angry red on the day. The new AQI is a worthwhile endeavour. Ironically, however, the main benefit of the AQI might be to prove to all of us why the index by itself is of very limited utility.

An air quality index is a way to combine measurements of multiple air pollutants into a single number or rating. This index is ideally kept constantly updated and available in different places. The AQI is most useful when lots of pollution data is being gathered and when pollution levels are normally, but not always, low. In such cases, if pollution levels spike for a few days, the public can quickly take preventive action (like staying indoors) in response to an air quality warning.

Unfortunately, that is not urban India. Pollution levels in many large Indian cities are so high that they remain well above any health or regulatory standard for large parts of the year (in some cases, almost the whole year). If our index stays in the “Red/ Dangerous” region day after day, there is not much anyone can do, other than get used to ignoring it. The index may actually hide when things are getting worse — in a city like Delhi, Diwali would look no different than other winter days on the AQI because both would fall in the same lowest quality rating.

In addition, the availability of data remains abysmally low. There is a handful of continuous monitoring stations running across the country. Many are not properly calibrated, while others are offline for long periods. Perhaps introducing the AQI will lead to pressure to improve monitoring infrastructure. If so, it will have served a valuable purpose. Nevertheless, it is rather odd that the index has come first, while the data necessary to use it properly is supposed to emerge at some unspecified future date.

Of course, it is a truism to say that a single step won’t suffice. There are ways to build on the AQI. For instance, this may be a good time to ask some questions about how we monitor pollution in general.

Installing pollution monitors by itself does not produce useful city-level air quality information. Monitors also need to be placed at the right locations and maintained properly. In Delhi, many monitors are placed near bus terminals or traffic intersections. What is measured here is almost certainly much higher than the city average, and not a good way to estimate city air quality as a whole. Countries like the United States have spent significant amounts of money to cover urban areas with a grid of carefully placed monitoring stations. It is time we put in place holistic pollution monitoring plans and required time-bound implementation by local governments.

But even with such plans, expensive ground monitoring all over India might be asking for too much. For all its problems, Delhi is a relatively bright spot when it comes to measuring air pollution. Most cities have virtually no representative monitoring, and in rural areas there is no data at all. We also cannot continue to say that we know nothing about air quality in most parts of the country just because an expensive and well-calibrated ground monitoring station isn’t present.

So, perhaps it is time to look at other options. The world has better technology today than it did 10 years ago. We should take advantage of improvements in satellite-based measuring techniques, and our regulators should use this type of data systematically so that we have some idea of what is happening to air pollution levels across the country.

More importantly, we need to remember that air quality monitoring doesn’t reduce pollution. Investing in a better thermometer is good, but it won’t make fever go away. Improving air quality will require innovation and dramatic reforms in how we regulate and monitor the sources of pollution, including industry and transport.

Many countries, including China, have introduced measures such as congestion pricing, market-based environmental regulation, environmental taxes and fines, cluster-based regulation and rating programmes for industries. These steps actually address the source of air pollution. Many of these innovations also move away from the command and control paradigm of regulation that still dominates India. By embracing reform of environmental regulation — and testing new ideas through regulatory pilots — we would not only improve environmental outcomes but also reduce industry costs, thus enhancing the prospects for economic growth…