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Delhi’s pollution levels in 2016-17 were 3-4 times above permissible limits

The annual permissible limits of PM2.5 and PM10 are 40 ug/m3 and 60 ug/m3 respectively as per the National Ambient Air Quality Standards.

delhi Updated: Jan 21, 2018 01:07 IST
Joydeep Thakur
Joydeep Thakur
Hindustan Times
delhi,delhi news,pollution
The ultra fine particles PM2.5, about 30 times finer than a human hair, are considered more harmful to humans as they can penetrate deep into the lungs and cause severe diseases(Sushil Kumar/HT PHOTO)

Over the past two years, the average yearly pollution levels in Delhi and its satellite towns remained at least three to four times above the annual permissible limits, says data by the Central Pollution Control Board (CPCB).

“The yearly average level of PM10 was found to be 273 micrograms per cubic metre (ug/m3) in 2016 and 2017, which is more than four times the permissible limit. The yearly average concentration of PM2.5 was 133 ug/m3, which is over three times the safe standards,” said a senior official of the CPCB.

The annual permissible limits of PM2.5 and PM10 are 40 ug/m3 and 60 ug/m3 respectively as per the National Ambient Air Quality Standards.

Particulate matter is a widespread air pollutant consisting of a mixture of solid and liquid particles suspended in the air. The ultra fine particles PM2.5, about 30 times finer than a human hair, are considered more harmful to humans as they can penetrate deep into the lungs and cause severe diseases. Scientists and doctors said that PM2.5 attacks the mucus membrane of lungs and respiratory passages. Exposure to such high levels of PM2.5 for a period of 5 to 10 years or more, could the damage lungs, the clinical manifestations of which might not show up in the initial stages.

“In the Pulmonary Function Test, there is a parameter Forced Expiratory Volume in one second (FEV1) which measures the air exhaled by a person in one second. Usually if a person can exhale 80% or more of the inhaled air in the first second then we consider it as normal. Clinical symptoms such as breathlessness while climbing stairs start showing once the reading falls below 80%,” said Arun Sharma, head of the department of community medicine at Delhi University, who is leading a project to study the impact of pollution on humans.

A study published in 2015 suggested that the Capital is home to the highest proportion of children with weak lungs in the country with over 40% students between eight and 14 affected by Delhi’s air. The study said 21% of the city’s children reported ‘poor’ lung capacity and another 19% fared as ‘bad’.

“While short-term exposure to high levels of particulate matter could affect respiratory tracts and eyes, long-term exposure of patients suffering from respiratory diseases could increase the severity of the disease. A healthy person might develop COPD if exposed to PM2.5 for a prolonged period as it affects reach the air sacs in our lungs,” said Raj Kumar, acting director of Vallabhbhai Patel Chest Institute

Data published in the Statistical Handbook of Delhi show that more than 61,800 people have died because of acute respiratory ailments between 2008 and 2016. The Capital registered an alarming increase in number of deaths due to respiratory ailments in 2010 and 2016 from the previous years. These were the two years where air quality was poorest in the past one decade.

Air quality in the Capital has, however, been much cleaner in 2017 compared to 2016, said an earlier data of the CPCB. While the number of days when pollution levels were ‘severe’, ‘very poor’ and ‘poor’ have gone down, days when air quality was ‘moderate’, ‘satisfactory’ and ‘good’ have increased.

“Meteorological factors play a key role in determining Delhi’s air quality. The data collected over past two years show that pollution peaks during the winter months when wind speed drops, the mixing height is lowered and the temperature drops. July and August have been found to be cleanest months in Delhi,” said D Saha, head of the CPCB’s air quality laboratory.

First Published: Jan 21, 2018 01:05 IST