About six days ago, India released a draft Air Quality Index. The idea is unexceptionable. The Index seeks to make air quality more easily comprehensible by reporting air quality not as dry numbers of raw concentrations but as colour-coded assessments of health impacts — good, moderate, poor, very poor, hazardous, etc. In this story out today, I argue, however, that for the index to be useful, fundamental problems in air quality assessments need to be fixed first.
This story, as things stand, is a followup to another story on air quality published about ten days ago. You need to, if you haven’t already, read the first one. Its PDF and, here, a link.
ps: Yesterday was diwali. And, while surfing to see how air quality was faring, I saw some eye-popping numbers. See these.
numbers from the civil lines air quality station, run by the delhi pollution control committee, as of 2215 hrs, yesterday. pm10 at 1000 (safety limit: 100). pm 2.5 at 995 (safety limit: 60). shortly afterwards, pm 2.5 climbed close to 1000 as well, reaching 999.85.
look at this chart. the way pm10 levels max out at 1000 suggests that the sensor might be set up to capture levels only till 1000 micrograms/cu m (understandably, given the safe limit is 60). i wonder what was the real extent of particulate pollution yesterday.
i have a fairly high degree of comfort with dpcc data. less so with the cpcb and spcbs. the cpcb, last night, was ridiculous. its sites were presenting allegedly realtime data for 2013 for parts of delhi. as for the spcbs, most of them were well below delhi. but one number from ahmedabad really made me sit up. look at pm2.5.