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Saved By the Wind: Why Chennai’s Air May Be Cleaner This Bhogi

Both of us were mesmerised by the beauty of the sea this morning. It was calm with wavelets rippling to shore gently but in rapid succession. The eastern horizon had a tint of orange, and the dappled skies had puffs of clouds that were rolling in from the northeast. The wind was a steady and brisk eeran blowing in from the east. As I stood a while on the seashore facing south, I could feel the balmy sea air pressing against the left side of my cheek. The sky above us was clear, as was the air over the sea. My walks with Palayam Anna through this month of margazhi (corresponds to mid-December to mid-January) have taught me this much – that a morning sea breeze brings warmth and clear visibility over the seas and land, while a land breeze brings chill and misty conditions all over.

Anna pointed to the dark cottonball rain clouds moving west and southwest with the breeze. “Mel maasiyaa koncham mazhai peyya vaippu irukku,” he said. ‘Mel maasi’ refers to well-defined moving rain clouds that shower raindrops as they move with the wind. When mel maasi rains happen in Margazhi, they are also called kola-mazhai as the drizzle adds its own art to the festive, elaborate kolams (geometric designs made of rice flour) made outside Tamil homes every morning during the month of Margazhi.

A photo of a kolam.

Palayam was excited about today’s eeran (blowing from the east). “There’s a good likelihood that it will swing towards the south as a kachan eeran (blowing from the southeast).” And then, completely unrelated, he murmurs as much to himself as to me: “Kadal romba ramyama irukku illai? (The sea is so beautiful, isn’t it?).” I was also admiring the spread of fishing boats bobbing about in the calm nearshore waters.

Air quality-wise, Palayam’s prediction about which way the wind will shift may be good news for Chennai. Tomorrow is Bhogi festival, the last day of the Tamil month of Margazhi – a day when old things are discarded, and the new year is ushered in with the auspicious Tamil month of Thai. “Good things are born when Thai is born.” “தை பிறந்தால், வழி பிறக்கும்,” is a popular saying. Ironically, just a day before the new year is born, air quality is at its worst. In another one of those rituals that have lost all meaning, and do more harm than good, people have failed to change with time. They burn old things, tyres, plastic trash and other garbage on Bhogi day. Not a single year goes by without the newspapers reporting deadly levels of pollution on Bhogi day. Some years are better than others, but all years are bad. For instance, air quality improved from very unhealthy in 2020 to unhealthy in 2021.

If Palayam’s predictions hold, air quality may not be as bad as on Bhogi day in 2020. The difference is not in how responsible Chennai residents are, but in how the wind behaves. Depending on how healthy you are, the air quality may only choke you and spare you death.

“Eeran adichaale pugasal ellathaiyum adichittu poyidumna. Karakathu thaan – kodai, vadamarai, nedun vadaiya adikkara kaathu than – pani kaathaa vanthu, naala thisaiyilum pugasala parappum.”

(‘The eeran sea breeze will blow away any low-hanging mist, brother. It is the shore breeze that blows in from the west, north west and north – that will bring in the chill and spread fog in all four directions.’)

As the sun climbs, the land heats up quickly heating the air above it. Hot air rises, and as the hot air rises, the sea breeze moves in, first gently, then steadily, pushing out and up the ground-hugging mist, fog or pollution.

Fishers setting out to sea early in the morning, time their launch from the beach to catch the shore breeze before it fully dies. They have a brief lull during which they can easily row before the sea breeze sets in and makes hauling the oars more difficult. The lull between when the shore breeze dies and the sea breeze takes over is the “iruvaa kaathu”. Iruvaa, as a term, applies equally to long-shore currents that are unmoving, not because they are still, but because of an equal stand-off between the south-flowing Vanni and the north-bearing Thendi current. There is no real “still” in the sea, only this kind of suspended animation when one movement is dying, and the other livening up.

I asked Anna if we can expect good air quality tomorrow despite the crazy burning that we are sure to indulge in. “That depends. The sea breeze is king. With a sea breeze during dawn, you can expect the pollution to clear up quickly. The air quality may be better than what it would have been with a land breeze. Given how it is blowing from the east today, there is a good chance that we have a sea breeze. We should be good.”

I returned home to check on newspaper reports about air quality in the city on Bhogi day in 2019, 2020 and 2021, and the wind conditions on that day in each of the three years. For this, I referred to the meticulous data that Palayam has been generating over the years. But before I get to wind and pollution, let me take a quick detour to tell you about the #ScienceOfTheSeas effort and the kind of data it is yielding.

Three years ago, on September 1, Palayam began recording micro-level meteorological data along the Urur Kuppam coast. Data collection was suspended between April 2020 and August 2021 due to COVID. The data gathering – a citizen science effort – was prompted by a conversation he and I had in 2017-2018, in the early days of conceiving the #ScienceOfTheSeas project, and the last year of the Urur Olcott Kuppam Vizha (‘vizha’ is Tamil for ‘festival’).

Given the importance of met data to the vocation of fishing, I recall asking him why fishers didn’t maintain detailed logs of meteorological observations or daily record of fishing activities the way some farmers did with rainfall and cropping data. He asked me what more use could such a recording offer that wasn’t already possible with his mental database and the baselines committed to the collective memory of his community. One does not replace the other, but merely brings in nuance and detail that would be helpful in understanding trends in these highly uncertain times, I explained. Palayam agreed.

After a few weeks of trial in July and August 2018, we set up what may be India’s first fisher science human observatory for systematically recording micro-meteorological data and ocean conditions in the village of Urur Kuppam. Palayam was that observatory, and I was his scribe.

We agreed on a few essential fields to begin with: date, nearshore current, nearshore sea conditions, midsea current, wind direction, likely fish behaviour and comments. These readings help understand how ocean conditions may be related to fish behaviour or decisions taken by fishers to fish or not to fish. More importantly, we hope that over time as the data builds up, we will have locally nuanced micro-level data that will help us identify signs of a changing climate and how fishers adapt to it.

The data, painstakingly gathered every morning by Palayam is recorded on plain paper and filed away. In June 2021, Logesh, a young graduate from North Chennai, transferred the data for September 2018 to March 2020 from paper to an Excel sheet. Much of the really insightful nuance is contained in Palayam’s open-ended comments. Because the initial transcription was done by a young intern, the richness of these comments was lost in the conversion. We decided to rectify that. In August 2021, Palayam began training me to read the winds and currents during our daily walks from 5:30 am to 6:15 am. Now, we have a more refined data sheet, and I work with Palayam Anna to transfer the data and his observations on a daily basis to the spreadsheet – he reads out in Tamil, and I enter it in English.

Source: Author provided

I referred back to the entries from January 2019, 2020 and 2022. There were no readings for 2021 because we had suspended the observatory due to COVID – the limitations of human observatories. Interestingly, the years with the worst air quality, 2019 and 2020, also coincided with a shore breeze on Bhogi day, and a shore breeze or near-shore breeze on the days preceding Bhogi.

This year and the last, the two days preceding Bhogi day had sea-breezes. Today’s sea breeze is pronounced, blowing straight from the east. For it to become a land breeze, it would have to swing more than 90 degrees to the north or to the south. Palayam suggests that such a wholescale shift is unlikely. “It may shift north or south to become a near-shore sea breeze blowing from the northeast or southeast. But chances of a land-breeze are low,” he said.

If his readings hold, we may be saved by the wind from the worst. Happy smokeless Bhogi and advance Pongal greetings.

The post Saved By the Wind: Why Chennai’s Air May Be Cleaner This Bhogi appeared first on The Wire Science.

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