Downloading pre-aggregated data is easy through QuantAQ Cloud, with a few important caveats.
How to download aggregated data for a device
- Navigate to a device page
- Click the "Download Data" button in the top right
- Select the date range you'd like to download data for (inclusive)
- Add a description
- Select the "Aggregated Data" tab (on the right of the "Full-Resolution Data" tab)
- Choose an Aggregation level
- Currently supported aggregation levels include 15 minutes, hourly, 8 hours and daily
- Click "Download Selected Data"
- Your data should show up in your data page shortly. Depending on the volume of data requested, this could take several minutes.
Notes about aggregated data
Averaging Calculations
Averaging is done naively across all data within the period. Averaging is not currently intended to match NAAQS or other specific averaging logic, and is provided for convenience only.
Completeness Criterion
Only periods with more than 75% of data present for the pollutant will be present in the aggregated data. For pollutants that don't meet this criterion for any individual period, their aggregated measurement will be omitted.
Aggregation levels
- "15 minute" provides four 15 minute long averages per hour: hh:00-hh:15, hh:15-hh:30, hh:30-hh:45 and hh:45-hh+1:00 in the local time of the device
- "hourly" provides twenty-four* 1 hour averages per day from hh:00-hh+1:00 in the local time of the device (*except for days with DST changes)
- "8 hour" provides three 8 hour averages per day, from 00:00-08:00, 08:00-16:00, and 16:00-00:00 in the local time of the device.
- "daily" provides one 00:00-00:00 average per day, in the local time of the device.
Date Range Limits
Date ranges are now unlimited for all durations of aggregated downloads.
Daylight Savings
Aggregated Data Downloads process aggregation periods in local time, including any daylight savings changes relevant for the period. To illustrate this by example, for a sensor located in the "America/ Los_Angeles" timezone, for which in 2023 Daylight Savings Time ends on Nov 5th, the "daily" average for Nov 5th will be from midnight Nov 5th PDT to midnight Nov 6th PST and will be an average of 25 hours worth of data. Alternately, "Hourly" averages for that sensor will contain 25 individual hourly averages for Nov 5th, 2023.
QuantAQ highly recommends working in UTC time, and only using local time for semantic reference.
FAQ
Why are there some missing values in my aggregated data?
QuantAQ Cloud automatically applies a completeness criterion of 75% for each pollutant in the aggregated data. If less than 75% of clean data is available for a pollutant during the period, the aggregated value is omitted. This could be due to a lack of entire datapoints during that period (for example, if the sensor was offline), or due to flagging for a single pollutant.
Is Aggregated Data available through the API?
Unfortunately, not at this time. We may add this support in the future.
Is downloading trailing averages supported?
Unfortunately, not at this time. We may add this support in the future.