KB, This is a great piece of news. Can claim 'some success' already for the Bus Day, well before the BMTC gets the feedback and they start  acting on it.

I am not surprised/excited about the fall in the pollution levels on Bus Day. But, post bus day the numbers have not come back to the original levels. Thats a factor telling us that there are indeed more commuters using 'cleaner' means...

Now, we need to devise strategies to sustain this. Any thoughts on that?

-Srivatsava

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 This pollution level data is interesting, but it would be best not to conclude anything from this data,  In any such data which could have fairly large statistical swings, it would be best to make a firm conclusion after some regular monitoring and statistical analysis that shows that this is a statistically significant change. As you can clearly see, the after bus day numbers are also lower than before bus day.  That could be an indicator that the bus day was a bigger success than we thought and people continued on the bus, or that because it was a Friday, it was a slow day or that this is the " noise" in the data.

It would be good to keep monitoring this, but best not to come to any conclusions.

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 Was there a control area where pollution data was compared for the same 3 days to ensure that we were measuring only the effects of Bus Day.  E.g. it could have been more windy on Feb 4 causing less SPM to hang around in the air.  

But if the control area e.g. showed no change in SPM but Marathahalli showed a 20% drop we can then make this claim.

Srivathsa

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Note Carbon Monoxide (CO) readings, highest drop by percentage on Bus day (2.0 to 1.4), but stayed almost the same after Bus Day (1.39).

Regardless, good data point. LEts have BMTC talk to KSPCB to get more measurements done around PT corridors.

Marathalli ORR signal was quick on Bus Day, I can vouch for that as I do the commute the same day almot same time. However, the speed at Mrathahalli ORR signal was compensated by a jam near HAL Airport signal. But then, didn't get many autos at HAL airport, and found more people looking for them. And now this pollution data. Mixed bag of data and observations to claim "success".

Want to remind all again - do take the post Bus Day survey if you haven't yet done that.

• Link here http://praja.in/en/form/2010/bus-day-survey-bmtc
• And, anyone can take it, you don't have to have a Praja account

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I'm not entirely convinced if this data actually supports the succes claimed by bus day.

If there had been monitoring at multiple points (say, at Silkboard, Kundalahalli cross & at KR Puram, in addition to Marathalli), & the data confirmed this finding, it might have been much more convincing.

Nevertheless, in the absence of multiple mobile monitoring units, we will just have to leave this as it were & look at the positives, I guess.

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This is a good observation, no doubt. But it would have been better if data was provided a week prior and after bus day. I am sure newspaper/s will not be patient for so long :)

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