Air Pollution » Air Quality and Public Health

The Central Pollution Control Board (CPCB) on Wednesday, 14th November, 2012 released the noise and air pollution data results in its annual press release just the next day after Diwali. The findings of the monitoring attributed the bursting of less noisy crackers for the declining trend in noise levels in Delhi vis-à-vis last year. Bangalore. Kolkata and Hyderabad also registered similar trends while no such trend was observed in Mumbai.

Air pollution on the other hand was found to have increased during this year’s diwali vis-à-vis previous year’s. CPCB has held adverse meteorological conditions (lesser average temperatures, decreased night time mixing height, low wind speed, and increased humidity as compared to previous year) and bursting of the less noisy crackers as the reasons for the same.

According to the CPCB press release, all the major pollutants - SO₂, NO₂ and PM₁₀ show an increase vis-à-vis last year’s diwali. (Table 1)

Delhi Pollution Control Committee (DPCC), in its data released for the media also shows an increase in all the pollutant levels this year on Diwali as compared to the last year. (Table 2)

A thing to note here is the difference in the pollutant range values provided by the two committees. This is because these committees have different monitoring stations in Delhi. However, one thing which is common to both the data is the fact that though the monitoring data is available for the entire day, but no specific time frame has been mentioned for which such an analysis has been done. This was crucial as an apt time period is vital to bring out the correct pollution levels as skewed time frames can bring down the ranges and the means of pollution data as observed and stated. This means taking the peak diwali pollution time frame is essential in order to correctly identify the pollution levels of the pollutants in question.

CSE takes a peek into the real time data provided on the DPCC website

CSE computed the pollution ranges and the averages and standard deviations of the major pollutants - SO₂, NO₂, PM₂ and PM_2.5  from the real time data availability facility provided on the DPCC website. A fixed time frame from 7:00 p.m.in the evening to 1 a.m. at night was taken on 13- 11-2012, i.e. on the day of Diwali. This time frame was selected to correctly specify the pollution levels caused as a result of Diwali as almost all crackers are burst during this time frame. Such a time frame is unspecified in the CPCB’s and DPCC’s analysis.

Following were the results of the findings surpassing those reported by CPCB or DPCC (Table 3)

Though the reported maximum pollution levels might be extremely high to be deemed as outliers for SO₂ and NO₂ due to their high to moderate standard deviations / heavy fluctuations in the pollution data; the averages adjusted to this fluctuation still portray massive levels of these pollutants.

With known hazardous health impacts of all these pollutants, it certainly cannot be concealed that pollution was not a factor this Diwali. In fact, the levels of these pollutants are extremely higher than those of previous year’s Diwali and surely are a cause of alarming concern.

- Shashank Gandhi