Understanding information shown on the chart
Each of the charts shows the amount of each respiratory virus in wastewater, prior to treatment at one of Metro Vancouver's five wastewater treatment plants. Results are sorted by sewerage areas, which are defined catchment areas around each wastewater treatment plant. Wastewater from homes and businesses within each area is collected and directed to a specific wastewater treatment plant.
The charts show two types of data related to each respiratory virus:
- Concentration in Wastewater: shows the amount of virus (copies/L) on the sample day
- Concentration in Wastewater – Adjusted for Wastewater Flows: shows the amount of virus (copies/day), which is the concentration of the virus adjusted for the volume of wastewater entering the wastewater treatment plant on the day the sample was taken. This helps account for dilution from rain and stormwater that enters the wastewater system.
Metro Vancouver is measuring the amount of wastewater entering treatment plants to monitor how it affects respiratory virus concentrations in wastewater. To date, these additional data generally show similar trends to that of the raw data for all respiratory viruses tested for in wastewater over time.
The science of testing for viruses in wastewater is evolving rapidly. The data shown in the charts should be considered as general trends and not specific daily measurements.
What the chart measurements mean
The charts show the concentrations of each respiratory virus detected in wastewater in copies per litre or copies per day. Copies are a measure of the virus's genetic material, which gives an approximation of the amount of virus present in wastewater.
If you click the "dynamic y axis" option, the scale on the y axis (vertical axis) will automatically adjust depending on the range of the data. This makes it easier to see values that may be very low or very high, which can be hard to accommodate within a single, static scale over the entire time period. Values can also be viewed by hovering over each bar.