Air Quaility Chelmsford

What is Air Quality?

Air quality is the term to describe how much pollution is in the air. When air pollution is high, air quality may be described as poor.

When air pollution is low, air quality may be described as good.

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In Chelmsford, the main forms of pollution within the air are:

Nitrogen Dioxide (NO2)

NO2 is a gas that is formed during the process of combustion. Petrol and diesel vehicles all produce NO2 as does energy generation and industrial processes.

Although NO2 may be produced during electricity generation used in electric vehicles, the vehicles don’t emit NO2 and can help to keep local NO2 levels down.

Particulate Matter 

Particulate matter is the term for solid particles or liquid droplets found in the air.

These particles put into two categories

PM10 : inhalable particles, with diameters that are 10 micrometers and smaller
PM2.5 : fine inhalable particles, with diameters that are 2.5 micrometers and smaller

Particulate emissions in the UK come from:

  • 38% from burning wood and coal in domestic open fires and solid fuel stoves
  • 16% from industrial combustion (non-domestic burning)
  • 13% from solvent use and industrial processes
  • 12% from road transport

Ozone (O3)

Ground level ozone is normally formed when other pollutants, including nitrogen dioxide react in sunlight.

On very sunny days, ozone levels can be high and can irritate and inflame the airways and lungs.

Air quality is generally good across Chelmsford.  However, air quality can be worse alongside busy roads and near to junctions caused by slow moving traffic.

Common sources of local air pollution are:

  • emissions from vehicle exhausts (nitrogen dioxide and particulate matter)
  • vehicle brake and tyre wear (particulate matter)
  • gas heating (nitrogen dioxide)
  • solid heating systems such as wood burners (nitrogen dioxide and particulate matter)
  • agriculture (ammonia which can form particulate matter)

Air Quality Monitoring

Chelmsford City Council operates a large air quality monitoring network consisting of four air quality monitoring stations and diffusion tubes deployed at more than forty sites.

Monitoring locations are located in known air pollution hotspots, alongside busy roads, at junctions where significant queuing occurs and at background locations not influenced by road traffic.


The national Air Quality Objectives for nitrogen dioxide are:

Annual Mean 40µg/m3

1-Hour Mean 200µg/m3

If a local authority finds any places where these objectives are not likely to be achieved, it must declare an Air Quality Management Area (AQMA) there.

Chelmsford City Council air quality monitoring information can be found within the Air Quality Dashboard and the Councils Annual Status Reports.

The 2023 Annual Status Report can be found online.

Currently no exceedances are being measured Chelmsford and the long term trend is of improving air quality.


Air Quality Management Areas (AQMAs)

Local authorities have a duty to declare those areas where the air quality objectives are not being met, or are likely to be shown to be at risk of not meeting them, and where people are likely to be regularly present, as Air Quality Management Areas (AQMAs).

In 2005 an AQMA was declared at roads in and around the Army & Navy junction. In 2012, the AQMA was amended to cover a smaller area.

In 2018 an AQMA was declared along a small stretch of the A414 in Danbury.

Due to improved air quality, in January 2024 Chelmsford City Council was able to revoke both of the AQMAs.

Air Pollution and Health

Exposure to air pollution can bring about short term symptoms and long term effects possibly leading to ill health or premature death.

Short-term symptoms

  • Coughing, wheezing and/or shortness of breath
  • Asthma attacks

Long-term effects

  • Stroke
  • Lung cancer
  • Respiratory conditions
  • Cardiovascular Disease

The effects of air pollution are particularly notable for groups of people that are more affected by air pollution:

  • older people
  • children
  • individuals with existing CVD or respiratory disease
  • pregnant women
  • communities in areas of higher pollution, such as close to busy roads
  • low-income communities

How can I improve air quality?

These are some small changes that everyone can make to help reducing pollution and to improve air quality:

  • Reduce your use of the car. Emissions of NO2 and particulate matter directly affect local air quality
  • Use sustainable travel. Walking, cycling and the use of public transport such as the bus, Park and Ride and the train are all important ways of travelling around Chelmsford and beyond
  • Dont idle! If it is safe to do so, turn off the engine if you are parked waiting or are queuing in traffic
  • Take a look at our web page to see how to reduce emissions from domestic burning

airTEXT Air Quality Forecasts and Alerts

Chelmsford City Council is a member of the airTEXT consortium that operates a free service for the public providing air quality alerts by SMS text message, email and voicemail and 3-day forecasts of air quality, pollen, UV and temperature are available online.

Residents and visitors to Chelmsford can sign up at the following link to receive the free airTEXT alerts and health advice by email, text message or voicemail alerts.

Local three day bulletins are available online and the forecast levels are also provided within the Air Quality Dashboard below.

The forecast is provided by airTEXT and represents the expected level of pollution for the whole area. The forecast doesn’t necessarily represent what people will experience at roadside locations.

Air Pollution Chelmsford

22 July


No action required
Effects unlikely to be noticed.

23 July


No action required
Effects unlikely to be noticed.

24 July


No action required
Effects unlikely to be noticed.

Health Advice

The index used to describe air quality is the daily air quality index (DAQI) for the UK. The index represents air pollution using a 1-10 scale divided into four bands: LOW (1, 2, 3), MODERATE (4, 5, 6), HIGH (7, 8, 9), VERY HIGH (10).

The health advice shown below for at risk individuals and for the general population is taken from the UK-AIR website provided by Defra.

Remember that air pollution levels are normally low and for most of the time you will not notice any effects on your health. It’s important that you do not become alarmed or panic when you receive an airTEXT alert. It is designed to help you ensure you have any necessary medication at hand and to prepare your day ahead to reduce your exposure.