Why smog refuses to go

Vibha Sharma in New Delhi

Health is a business. It cashes in on the fear factor of people desperate to protect themselves. Ever since smog began engulfing the Capital, many businesses promising ‘pure air’ have come up and many more will in due course of time. There are ‘FDA-approved’ oxygen cans, fast selling pollution masks, air purifying plants to expensive electrical air purifiers… The environment-generated health emergency in the NCR has put on risk everyone, including unborn children.

A familiar sight, year after year

On November 8, a day after Diwali, as the sun struggled to come out of the smog-ridden haze, casting a gloomy shadow over the skies, it was not the firecrackers defying the Supreme Court ban, but the futility of the situation that struck the loudest. Around this time, every year, the Capital region chokes as climatic conditions make it conducive for hazardous particulate matter (PM10 and PM2.5), a deadly cocktail containing soot, smoke, metals, nitrates, sulfates, dust, water, etc., settle over its skies, turning them into an ominous grey.

As temperatures drop and wind speed slows down in the land-locked region, the concentration of air pollutants increases both outdoors and indoors. The Delhi-NCR turns into a toxic gas chamber. The number of patients with respiratory problems increases and pollution control agencies like the Supreme Court-appointed Environment Pollution Control Authority (EPCA), the CPCB, environment ministries and words like AQI start making the headlines.

Incidentally, AQI (air quality index) is a number used by the government agencies to communicate how polluted the air is. However, as a top government functionary points out: “Any improvement is possible only if pollution control is made a day-to-day effort. Knee-jerk reactions are not a solution to such problems. How can you ban private vehicles without providing an alternative?”

Local factors at play

Experts say stubble burning contributes around 20 per cent of the problem that recurs in the NCR year after year, but the maximum — 80 per cent — is due to local activities like vehicular traffic, industrial pollution, construction, garbage burning and, of course, firecrackers.

The NCR today is a concrete jungle with very little green cover. Talk to residents and they will tell you about those times when population was less and trees more. End of October usually saw light rains, but, the past few years have seen a change in the pattern of Western Disturbances and other systems that provide speed to winds. The fact is that unless the land-locked NCR receives strong winds or rains, suspended pollutants do not dissipate, rather their severity increases.

Fog + pollutants = Smog

Wind speed and direction are governed by atmospheric systems. These could be cyclonic circulation over Rajasthan or Haryana, a WD from Pakistan or a low pressure building up in the far away Bay of Bengal. This year, the Northwest received consequent WDs, leaving no scope for the winds to establish. While the winds remained light during the day, there was almost no movement of air at night when temperatures dipped, making it conducive for toxic pollutants and particulate matter to gather and hang low near the surface of the earth.

Fog builds up when temperature is low, wind movement is light and there is moisture in the air. Add to it deadly pollutants, and it is perfect recipe for smog. This year, the build-up started in October. The situation was further aggravated when light winds from the Northwest carried in stubble particles. However, a welcome gap between two WDs caused the winds to change direction, pick speed and clear air two days before Diwali. A low pressure over the Bay and a cyclonic circulation over Rajasthan further added force to these winds.

On Diwali, there were almost no winds. Maximum temperatures on the day were also markedly below normal (-5.1°C or less) in Haryana, Chandigarh and Delhi, adding to the build up of the smoggy cover over the region. But then weather conditions are such during this time of the year, with monsoon having withdrawn and winter approaching. The fact is that if winds are strong and get the conducive direction, pollution will remain low in NCR. If they slow down, the pollution buildup begins. The only way out is to not let pollution accumulate during this time of the year. But that is a challenge that needs to addressed throughout the year, not just around this time.