Yes, it is that time of the year when along with ads on festival discounts, newspapers will soon be awash with public advisories on the ills of chemical-laced idol immersions and bursting of crackers. Every year, this pitch falls on deaf ears.

Hundreds of half-melted chunks of Ganesha idols are still floating around in the Yamuna. Since last month, their noxious chemicals have made the polluted waters more poisonous. This week, the Durga Puja will culminate in hundreds of immersion into the Yamuna.

The air will not be spared either. Last Diwali, fireworks fouled up Delhi’s air so much that it broke three years’ pollution record. The thick smog was compared to the world’s worst, leaving people gasping for breath for days on end.

For a culture that reveres its rivers, mountains, trees, animals and the earth, how did Indian festivals become so reckless?

There is no tradition of using chemicals and heavy metals in idol making. On the contrary, customs specify clay and straw as the main ingredient, and that too for a reason.

Clay gives form to the formless and dissolves with immersion, merging with the elements and thus, completing the circle of life.

But now with idol-making reaching an industrial scale, statues are modelled out of plaster of paris, which takes years to fully dissolve in water. Instead of natural vegetable dyes, they are now coloured in paints containing heavy metals such as mercury, cadmium and lead, which poison the water for good.

Last year’s idol immersions shot up Biochemical Oxygen Demand (BOD), which indicates the level of organic pollution, to 38 mg/l at some ghats on the Yamuna. The Delhi Pollution Control Committee says that for any aquatic life to survive, the BOD must not exceed 3 mg/l.

Yet, Delhi is again set to conclude the celebrations in the Yamuna. A proposal to conduct visarjan of all the idols at Chittaranjan Park in a temporary pond in the neighbourhood was shot down because of lack of space and will.

Many play down these risks by justifying a festival as a one-off phenomenon. But they add up. Anyway, can one of the world’s most polluted capitals afford such indulgence?

No religious excuse can justify environmentally disastrous rituals like clogging and polluting water bodies with idols or turning the air foul with sulphur and gunpowder smoke.

Even the Delhi High Court made it clear. “Diwali, though called a festival of lights, has religious context only in illuminating the buildings traditionally with diyas. There is nothing to suggest that bursting of firecrackers is related to any religious tenet,” the court noted two years ago.

But why do we need so much coaxing to stop doing something we know is bad for us? The Yamuna’s toxic water is not just an assault on the olfactory system, it also poisons the groundwater and any fruit and vegetable that grows on its floodplain.

The lethal fumes from Delhi’s massive fleet of vehicles, emissions from coal-fired power plants, and dust from numerous construction sites are already filling up our lungs. We have to be suicidal to add smoke from Diwali crackers to this list.

In 2010, the Central Pollution Control Board issued guidelines on idol immersion, a complete user’s manual to make the process eco-friendly.

Two years ago, the National Green Tribunal banned dunking of non-biodegradable idols into water bodies. But these instructions are hardly followed.

Authorities must help by building dedicated idol immersion tanks but that won’t make the festivals less toxic. As long as there is demand for cheaper, chemically coated statues, the market will thrive.

The same is true for the sale of crackers. Last November, the Supreme Court had suspended all licences to sell fireworks within the National Capital Region. Two weeks ago, it permitted resumption of sale, on certain conditions and by reducing the number of licenses. But as enforcement records of such bans show, there is no point in issuing orders that cannot be implemented.

Unless, of course, citizens themselves commit to greener and cleaner festivals.