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jovanovski Feb 06, 2020 03:29 PM
Why in the calculation of EAQI we include the running 24 mean of PM10/PM2.5, instead of the latest measurement only? Won't this create issues when detecting sudden rises in pollution?
Replies (4)
jovanovski Feb 06, 2020 03:42 PM
For example, if in the past 22 hours PM10 is around 10mg/m3 at a certain spot, and then suddenly a factory starts polluting the air with 500mg/m3 for 2 hours in the same spot, the 24h average will be just 50mg/m3.

That means the EAQI will be quite low for those 2 critical hours, but the air is polluted like crazy outside, so people wouldn't understand just how bad it is outside if they rely on the EQAI.

Can someone help me understand this better?
EEA Feb 07, 2020 11:20 AM
Dear M. Jovanovski,

Thank you for contacting the European Environment Agency (EEA).

The Air Quality Index aims to offer information on the air quality situation focusing on the health impacts of short-term exposure to air pollution. You can see that health related recommendations have been included in the most recent update. Therefore, the reason to consider 24-hours mean and not the hourly values for PM is that the World Health Organization has set PM guidelines and relative risks for daily values of PM, and not hourly. In any case, be aware that you can always check the hourly values at EEA´s up-to-date viewer. Please see:[…]/up-to-date-air-quality-data .

With kind regards,
EEA Enquiry Service
jovanovski Feb 11, 2020 10:07 PM
Thank you for your answer!

I fully understand the need for a 24h guideline. But the issue with taking in a 24h mean instead of the hourly measurements is still valid as stated above. Let's break the example down:

PM10 measurements = [10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 500, 500]

The PM10 average at the last hour of the measurements will be 50. Thus the EAQI (if it only takes this parameter) will be 33.3
But if we are to take only the last hourly measurement of PM10 in the EAQI calculation, instead of the mean, we would get an EAQI of 333.3

The reality of that hour is that outside is extremely polluted, and the higher EAQI would match the situation. If we are to use the lower one that uses the mean, people would believe it's still OK to go outdoors, thus will suffer from the pollution.


I just wanted to make a point with this example as to why the 24h mean could mean misinformation for the current situation. Is it possible that you can provide me with a contact email of someone in the EEA that would look into this matter in more detail by any chance?

Thanks for the time you spend reading this, I know you guys must be busy :))
EEA Feb 17, 2020 04:03 PM
Dear M. Jovanovski,

We acknowledge receipt of your message and appreciate you sharing your views on the matter.
Kindly note that your message was transferred to our experts for consideration.

With kind regards,
EEA Enquiry Service