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Varanasi, Allahabad air over WHO pollution limits on most days in August

On more than 90 per cent of the days in August this year, pollution levels in Varanasi and Allahabad exceeded World Health Organisation (WHO) guidelines for acceptable levels, an IndiaSpend analysis of data recorded by #Breathe, our 12-city network of air-quality monitoring stations, shows.

This can be a lethal situation because a day with a high concentration of airborne particulate matter (PM) can lead to short-term mortality, according to a WHO report. This is when an ill person dies within 30 days of a visit to a hospital, or during the visit, according to a Journal of Epidemiology article in 2003.

The WHO guideline for 24-hour average for PM 2.5 is 25 per cubic metre, and it reflects “the concentrations at which increased mortality responses… are expected based on current scientific findings”.

PM 2.5 are particles measuring less than 2.5 µm (micrometre, one millionth of a metre), a fifth of the size of a fog or cloud water droplet. The main source of these is vehicles, boilers and power plants.

People with breathing difficulties such as asthma, and lung and heart diseases are most at risk to PM 2.5.

A WHO report suggested that a country regularly exceeding the 24-hour limit “undertake immediate action to achieve these levels in the shortest possible time”. And Varanasi exceeded the limit 96 per cent of the time this August — 27 out of the 28 days monitored.

The most likely reason for this could be vehicular pollution. Both Varanasi and Allahabad were badly hit by flooding in August, 2016, leading to traffic congestion.

On 26 days — 93 per cent of the days examined — Varanasi’s PM 2.5 levels averaged over 30 per m³. A reading between 30 and 60 is regarded as “satisfactory” under the Indian government’s Air Quality Index (AQI) guidelines. This assessment suggests that only a sensitive few will feel its effects, and then too only breathing difficulties.

But the WHO warns that a level of 37.5 is associated with approximately a 1.2 per cent increase in short-term mortality. Of the days monitored in Varanasi, 64 per cent (18 days) had an average level of over 40, and 54 per cent (15 days) had an average PM 2.5 level of over 50 — associated with an approximated 2.5 per cent increase in short-term mortality, according to the WHO report.

On 11 days out of the 28 examined (39 per cent), the level in Varanasi was over 60, classified as “moderately polluted” under the Indian government’s guidelines, and “may cause problems for people with asthma, heart problems, or children and the elderly”.

In Allahabad, 28 days in August (90.3 per cent) were over the WHO guideline, on an average. PM 2.5 levels were over 30 per m³ on 24 days — 77 per cent of the time. On four days of the month, the level was over 60.

On August 25, 2016, when Varanasi was celebrating Krishna Janmashtami, the city suffered its worst 24-hour average of 118.6 –274 per cent higher than the WHO’s recommended limit. By WHO estimates, this would translate to about a 9.4 per cent increase in short-term mortality.

The day began with an average level of 151.8 between 1 am and 6 am — six times the WHO limit. The levels then dipped, but spiked again in the evening, ending at an average of 136.7.

The Indian government classifies this as “very poor” conditions, which, if endured too long, can lead to breathing problems, particularly for people with lung and heart ailments.

In Allahabad, August 29, 2016, was the worst day, where the 24-hour average for PM 2.5 concentration stood at 93.4 — associated with roughly a 6.8 per cent increase in short-term mortality. In the early morning — 12 am to 4 am — the average reading was 107.4.

Fridays showed the lowest levels in Varanasi at an average reading of 43.4, while Wednesdays had the best conditions in Allahabad, averaging at 35.5. 

Thursdays, with an average PM 2.5 level of 64.6, were the worst in Varanasi, while Tuesdays were the worst in Allahabad — the average PM 2.5 level was 47.1.

The worst hours extended from 6 pm to midnight, with an average PM 2.5 concentration of 71.4 throughout Varanasi and 46 in Allahabad. Further, 9 pm was the worst single hour, on average, in Varanasi, with a PM 2.5 concentration of 81.6, and 2 am the most toxic in Allahabad at 57.9.

In both cities, 3 pm was the safest hour of the day to be outdoors, the levels averaging at 32.6 for the month in Varanasi, and 32.1 in Allahabad.

But the lowest levels are still over WHO recommendations.

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