Measuring our progress

Use this page to understand how the government assess our progress and how we're currently performing. 

We introduced Bath's Clean Air Zone to help the city meet UK air quality legislation. The legal limit for concentrations of nitrogen dioxide (NO₂) is 40μg/m³ as an annual average.

We were directed by the government to reduce levels of NO₂ in the city in the shortest possible time.

The Joint Air Quality Unit (JAQU)

Our progress is independently verified by the Joint Air Quality Unit (JAQU).

JAQU State Assessment Criteria

The Joint Air Quality Unit assesses our air quality data and reporting, to determine if we have met criteria of four key assessment checkpoints.

The Government has confirmed that we have successfully reached State 2. This means that our measured NO₂ concentrations in scope within the Local Authority Air Quality Plan are below or equal to the annual average limit value (40μg/m³) for one calendar year. 

Read JAQU's B&NES Air Quality Monitoring State 2 Summary (2021)

Read JAQU's B&NES Air Quality Monitoring State 3 Summary (2022)

You can expand on the following items to understand how our progress and success is measured.

1. State 1

   Completed

   On track to achieving success.

   Measures are having a positive impact on air quality. Data indicates that further NO₂ concentrations will not exceed the annual average legal limit.

2. State 2

   Completed

   Have achieved success.

   All measured NO₂ concentrations are below or equal to the annual average legal limit of NO₂ concentrations for one calendar year.

3. State 3

   Completed

   Demonstrated to be maintaining success.

   All measured NO₂ concentrations remain below or equal to the annual average legal limit of NO₂ concentrations for a second calendar year.

4. State 4

   Pending

   Likely to continue to maintain success, ready to confirm legal obligations have been met.

   Data analysis shows the local authority is likely to continue to meet its legal obligations and unlikely to breach the annual average legal limit of NO₂ concentrations.

 

Our success

Since the launch of the zone and by the end of 2022:

• nitrogen dioxide concentrations have reduced across Bath, with an average reduction of 26% inside the Clean Air Zone. This is an average annual reduction of 8.5μg/m3
• nitrogen dioxide concentrations have also reduced in urban areas outside the Clean Air Zone, with an average reduction of 27%. This is an average annual reduction of 7.1μg/m3 
• vehicle compliance rates across all vehicle groups have improved, which means cleaner vehicles are driving across Bath
• Over 900 vehicles were replaced with cleaner versions through our financial assistance scheme

What happens next

We are now working towards achieving State 3, to demonstrate that we are maintaining our success. To achieve this, all our measured NO2 concentrations in scope within the Local Authority air quality plan must be below or equal to the annual average limit value (40μg/m3) for a second calendar year.

How you can help

You can help us to maintain the improvements that we've made.

Please consider if you can:

• travel more sustainably, walk, wheel or use public transport
• carpool, or consolidate your trips if you need to drive
• group together home deliveries when ordering online
• turn your engine off while waiting

You can keep updated with the progress of Bath's Clean Air Zone on Facebook and Instagram.

Read more about the Government's NO2 programme.