What Ravana Effigy Smoke Does to the Air You Breathe in October

By mid-October, the air over most north Indian cities is caught between two seasons. The monsoon's cleaning effect is gone. Cold air has not yet arrived to flush pollutants upward. What stays near the ground is a thickening mix of vehicle exhaust, construction particulates, and the first wisps of stubble burning from Punjab and Haryana. The Central Pollution Control Board has recorded some of its highest 24-hour PM2.5 averages of the year in the October-to-November window, before Diwali even arrives. Ravana Dahan falls into this window.

A large Ravana effigy is not a bonfire of dry wood. The frame is typically bamboo and mild steel wire. The outer shell is papier-mâché, cloth, and synthetic fabric. The fill includes sawdust, straw, and firecrackers packed into the limbs and torso to produce the visible bursts. Each of those materials burns differently. Bamboo burns relatively clean. Synthetic fabric releases hydrogen chloride and volatile organic compounds. The firecrackers add sulphur dioxide, barium compounds from green-coloured bursts, and fine metallic particulates. A single large effigy can release a concentrated plume of PM2.5 and PM10 that, in still October air, does not disperse quickly. At a major ground with multiple effigies burning simultaneously, local air quality in the immediate area can spike to levels that would register as severe on the AQI scale for the duration of the burn and for some time after.

The respiratory system's first line of defence is the mucociliary escalator, the layer of mucus and tiny hair-like cilia that traps particles before they reach the lower airways. PM2.5 particles, defined as those smaller than 2.5 micrometres in diameter, are fine enough to bypass this system entirely and deposit in the alveoli, where gas exchange happens. For a healthy adult standing a reasonable distance away, one evening's exposure adds a small load to what the lungs already handle. For someone with asthma, chronic obstructive pulmonary disease, or ischaemic heart disease, the same exposure can trigger bronchospasm or worsen cardiac strain. Children's airways are narrower and their breathing rate per body weight is higher, so they inhale proportionally more of what is in the air around them. The Indian Council of Medical Research has identified ambient air pollution, including episodic event-based spikes, as a contributor to the country's rising burden of non-communicable respiratory disease.

Smoke from a burning effigy follows the wind. Standing upwind of the effigy at Dussehra is a different exposure from standing downwind in the crowd. At fifty metres upwind, the plume has not reached you. At fifty metres downwind, you are inside it. The difference in PM2.5 concentration between those two positions during an active burn can be several hundred micrograms per cubic metre, the kind of gap that matters for anyone with a sensitive airway. Arriving early and leaving before the burn, or watching from a rooftop or elevated position that is upwind, reduces contact with the densest part of the plume. Choosing a ground that uses fewer firecrackers in the effigy fill reduces the metallic and sulphurous fraction of the smoke.

An N95 respirator, worn correctly with the nose clip pressed down, filters more than 95 percent of airborne particles above 0.3 micrometres. A surgical mask does not. A cloth mask does not. If you or someone with you has a respiratory condition and plans to attend, this distinction is worth acting on rather than filing away. Anyone using an inhaler should carry it. Children and elderly family members with known lung or heart conditions are the group for whom a doctor's input before attending is a reasonable step, not an overcautious one. The evening itself is worth attending. Knowing what you are standing in lets you make a considered choice about where you stand.

The October air carries more than any single evening adds to it. Ravana Dahan is one concentrated hour inside a month-long deterioration. The effigy smoke is real and measurable. So is the context it arrives in.