The council reports reduced nitrogen dioxide across its monitoring network. Annual averages are not a live air-quality reading. Transport projects, vehicle standards and other factors can all affect air quality.
City council · transport operators
−30%
Change in monitored nitrogen dioxide
Council-reported reduction across its monitoring network. Does not describe all pollutants or every location.
Southampton City Council · 2019–2024
Checked 3 October 202640µg/m³
Annual nitrogen dioxide legal limit
Annual concentration objective, not a city measurement.
Southampton City Council · As cited March 2026
Checked 3 October 202622.2m
Local bus passenger journeys
Journeys on services in the city; includes repeat trips and visitors, not unique residents.
Southampton City Council / DfT · 2024/25
Checked 3 October 202621.7m
Local bus passenger journeys, previous year
Same council/DfT release.
Southampton City Council / DfT · 2023/24
Checked 3 October 2026Southampton City Council
Use the city council for local road defects, street lighting and parking. National Highways deals with the strategic road network.
Open official service → More help| Measure | Southampton / area | Period | Source |
|---|---|---|---|
| Change in monitored nitrogen dioxide | −30% change · Southampton | 2019–2024 | Southampton City Council |
| Annual nitrogen dioxide legal limit | 40 µg/m³ · England | As cited March 2026 | Southampton City Council |
| Local bus passenger journeys | 22.2m journeys · Southampton | 2024/25 | Southampton City Council / DfT |
| Local bus passenger journeys, previous year | 21.7m journeys · Southampton | 2023/24 | Southampton City Council / DfT |
4.14%
% · June 2026
Includes every mapped likelihood band, including very low. Denominator is all NRD 2023 properties in the local authority, including non-residential properties. Modelled risk with defences; not a prediction that this percentage will flood.
36
spills · 2025 · Portswood Sso
Named outfall (SWS00674), discharging to RIVER ITCHEN ESTUARY; not a city or harbour total. Spill count uses EA 12/24-hour method. Duration is monitored discharge time, not sewage volume or a real-time bathing safety result. Monitor operational for 99.91% of reporting period.
380.21 hours
hours · 2025 · Portswood Sso
Named outfall (SWS00674), discharging to RIVER ITCHEN ESTUARY; not a city or harbour total. Spill count uses EA 12/24-hour method. Duration is monitored discharge time, not sewage volume or a real-time bathing safety result. Monitor operational for 99.91% of reporting period.
99.91%
% · 2025 · Portswood Sso
Named outfall (SWS00674), discharging to RIVER ITCHEN ESTUARY; not a city or harbour total. Spill count uses EA 12/24-hour method. Duration is monitored discharge time, not sewage volume or a real-time bathing safety result. Monitor operational for 99.91% of reporting period.
18
spills · 2025 · Woolston Sso
Named outfall (SWS00969), discharging to RIVER ITCHEN ESTUARY; not a city or harbour total. Spill count uses EA 12/24-hour method. Duration is monitored discharge time, not sewage volume or a real-time bathing safety result. Monitor operational for 99.14% of reporting period.
78.07 hours
hours · 2025 · Woolston Sso
Named outfall (SWS00969), discharging to RIVER ITCHEN ESTUARY; not a city or harbour total. Spill count uses EA 12/24-hour method. Duration is monitored discharge time, not sewage volume or a real-time bathing safety result. Monitor operational for 99.14% of reporting period.