Note: This data is not a representative sample. Voluntarily contributed measurements may carry
various biases, potentially towards both better and worse CO₂ readings than typical. A journey is measured
for as long as the contributor stays on board, so it does not cover a whole line.
Filters
Time Filters
Date range:to
Months
Days of Week
Hours (UTC)
Times are UTC. Showing local clock time needs a location per route, which the route file does not carry yet.
Group & Sort
Split by:
Period:
One data point per:
i
Every journey still counts, but each transit line carries the same total weight no matter
how often it was measured. A journey on a line with 50 measurements counts one fiftieth as
much as a journey on a line measured only once.
This stops one frequently measured line from dominating the result. Unlike
Line (journeys averaged), it keeps the spread between individual journeys
instead of collapsing each line to a single number.
Because journeys carry different weights, individual points and outliers are not drawn in
this mode — only the box, whiskers and median.
Min. journeys per group:
Show topby, display order:
Results
Chart:
Group by:
Colour by GO IAQS air quality category:
Good (<800 ppm)
Moderate (800–1400 ppm)
Unhealthy (>1400 ppm)
Table
Group
Journeys
Lines
Median CO₂
90th pct
% Good
% Unhealthy
Comparison Mode
Compare up to 5 independently filtered sets of journeys side by side.
One data point per:
i
Every journey still counts, but each transit line carries the same total weight no matter
how often it was measured. A journey on a line with 50 measurements counts one fiftieth as
much as a journey on a line measured only once.
This stops one frequently measured line from dominating a group. Unlike
Line (journeys averaged), it keeps the spread between individual journeys
instead of collapsing each line to a single number.
Because journeys carry different weights, individual points and outliers are not drawn in
this mode — only the box, whiskers and median.
applies to all groups
i
Keeps only the transit lines that appear in every group, so each group
describes the same set of lines instead of a different one. That way a difference between
groups reflects the thing you filtered on, rather than one group simply happening to contain
busier or better-ventilated lines.
Matching works at the level of the line (the OSM route relation) —
not the individual stations. Two journeys on the same line can still cover different stretches
of the route, so trip length and which section was travelled continue to play a role.