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Air quality

Solar Pod on site, supplying electricity and hot water to site accommodation.
A solar and hydrogen power unit is being used at an HS2 construction site.

Air quality

Emissions of air quality pollutants in the UK contribute to local, regional and international air pollution levels. High concentrations of air pollutants are known to be harmful to human health and the environment.
According to the National Atmospheric Emissions Inventory, Road Transport accounted for 11% of particulate matter emissions and was the highest contributor at 31% of oxides of nitrogen (NOx) emissions across the United Kingdom in 2018.

Improving the quality of the air we breathe is an important part of the Government’s 25 year Environment Plan. The plan sets out how to improve the environment within a generation and leave it in a better state than we found it.

By moving high speed trains on to a new, dedicated intercity line, HS2 will free up space on the existing rail network to run more local and regional commuter trains. With more reliable, local frequent stopping services available, people will be able to shift from road and air travel to rail which will improve the environment and the quality of the air we breathe.

On this page you will learn about what HS2 is doing to avoid and minimise our impacts on local air quality as we build the network.

In addition, there is also further information on quality assurance, and links to Environmental Statements and Information Papers.

Key definitions

Air quality

Air Quality describes the ‘cleanliness’ of the air we breathe and the condition of the air within our environment. The quality of air is measured by the level of pollutants it contains. A pollutant is the wrong amount of a substance in the wrong place or at the wrong time.

Air Pollution

Air Pollution is the release of particles and gases into the atmosphere. These emissions can be natural or man-made and may impact human health, plants and animals.

Nitrogen oxides

All combustion processes in air produce oxides of nitrogen (NOx). Nitrogen dioxide (NO2) and nitric oxide (NO) are both oxides of nitrogen and together are referred to as NOx. Air quality standards are measured by the level of NO2. The main source of NOx is road transportation, followed by the electricity supply industry and other industrial and commercial sectors.

Particulate matter

Particulate matter (PM) comes from both man-made and natural sources. It includes soot, smoke, sea spray, dust, pollen, and liquid droplets. PM10 refers to particulate matter which is 10 micrometres or less in diameter. The biggest sources of PM10 emissions are road transportation and the building industry.

HS2 in operation

Delivering HS2 will enable the shift from road and air to rail, improving the quality of the air we breathe and supporting the transition to a net-zero carbon economy by 2050.

HS2 will be powered by electricity from a rapidly decarbonising national grid. Unlike cars, lorries or planes, HS2 trains will not emit air quality pollutants during operation.

Cleaner Air and Cleaner Construction

Take a tour of the latest clean construction machines.

Minimising emissions while designing and constructing HS2

We are raising the bar on air quality standards and leaving a legacy for future infrastructure projects.

At HS2 we prioritise minimising emissions when designing and constructing the railway. We aim to be a good neighbour every single day, by respecting the people and communities we impact, being sensitive to their needs, and earning our social licence to operate.

We are setting high standards for the construction industry and will an important legacy through innovations in construction, and management of emissions and dust.

Designing out emissions

Through our design stage we aim to avoid and minimise emissions during construction and operation. Here are some examples of this approach.

Transporting excavated material by rail

We are cutting emissions by transporting excavated material by rail rather than lorries on highways, cutting emissions and improving air quality.

Case study: In partnership with London-based stakeholders, HS2 has provided an assurance that we will transport construction materials by rail, rather than road whenever possible. This means that we could have the potential to prevent approximately 55,000 lorry movements in the Camden area and reduce emissions by around 34%.

Limiting emissions from highway vehicles

Once pollutants have been emitted from a vehicle; it is very difficult to remove them from the atmosphere. HS2 has adopted a policy of setting vehicle emission standards for construction vehicles and Non-Road Mobile Machines. We have also introduced targets for the use of ultra-low emission vehicles, enabling us to reduce emissions at source.

Designing emissions out of HS2 stations and depots

HS2 buildings are designed to avoid emissions during operation, for example through heating and cooling of the building. We assess the full design life of the building and the future supply of energy and design out emissions wherever we can.

Preventing dust and emissions during demolition

We implement a best practice dust management mitigation protocol through demolitions, earthworks, construction and movement of spoil away from sites. All dust mitigation measures implemented across our sites are set out in the Code of Construction Practise (CoCP). Some of which include:

  • Ensuring we strip the interior of the building before commencing demolitions. Buildings or structures to be demolished are sprayed with water and / or screened prior to and during demolition activities.
  • Burning of materials / spoil is prohibited on site.
  • Vehicles transporting materials within or outside of the construction site should not be overloaded. Deliveries entering or leaving the construction site should be covered to prevent material and dust spillages.
  • We surface and maintain haul routes to control dust emissions. Haul roads are inspected regularly and methods to clean and suppress dust on haul routes (including watering) should be implemented.
A hybrid power excavator working on an HS2 site.
An electric powered telehandler on a construction site.
An electric powered mini dumper used on an HS2 archaeology site.
Construction plant power. A hybrid power excavator at work at HS2's Euston construction site. An electrically-powered telehandler at an HS2 West London site. An electrically-power mini dumper.

Cutting emissions during construction

We aim to avoid emissions during construction, but where this is unavoidable, we have set stringent limits and do everything we can to minimise public and workforce exposure.
Air quality can be affected by construction in a number of ways, including:

  • Exhaust fumes from vehicles and machinery;
  • Exhaust fumes from changes to traffic flows due to road closures and diversions; and
  • Dust from on-site activities.

We are taking action to minimise our impact on air quality through a range of measures (our mitigation measures).

Air quality emissions from vehicles and machinery and traffic flows

  • We have set the lowest emission standards available for all contractors’ vehicle engines (e.g. lorries, vans, and cars), as well as set targets for contractors to go beyond this as technology improves. This currently includes Euro 6 requirements for all lorries across the route.
  • We have set industry leading emissions standards for all machinery (e.g. excavators, dumpers, large cranes and piling machines).
  • Contractors use designated lorry routes to minimise the use of local roads.
  • We send our route plans to the local authority to review if there are going to be more than 24 vehicle movements per day.
  •  We produce Local Traffic Management Plans with local and highway authorities and the emergency services before the start of work.
  •  We train our lorry drivers on how to reduce their emissions.

Full details of all our mitigation measures are in our Code of Construction Practice.

Dust Control

  • We require all our contractors to control and limit their dust, air pollution, odour and exhaust emissions during works.
  • Our contractors use a range of dust management methods including damping down using mobile water sprayers, handheld hoses and water cannons. Damping is when water traps pollutants stopping them from escaping into the air. Some machinery used in demolitions is specifically fitted with water sprayers to allow for damping down at source.
  • We monitor the particulate matter (PM) levels at key sites along the route to make sure our mitigation measures are appropriate for the level of pollutants at a specific site. We cater each control to each specific activity.

How do we monitor air quality?

We continuously monitor real-time dust concentrations and nitrogen oxide at key sites along the route, as determined by the Institute of Air Quality Management’s best practice guidance.

In line with this best practice guidance our on-site dust monitors trigger alerts, which provide real-time feedback to contractors, allowing us to respond quickly to emissions wherever and whenever they occur.

We undertake NO2 diffusion tube monitoring at key locations, identified in the Environmental Statement, where significant impacts from our works may occur.

Our air quality monitoring surveys add to existing national and local monitoring activities by Defra, local authorities, communities and academic institutions.
We produce monthly monitoring reports per Local Authority area. We also produce an Annual Air Quality Report which highlights compliance against our emission requirements as well as details the monitoring undertaken in a year.

Driving industry-wide innovation on air quality

We are working with industry leaders and academia to encourage innovation and set new standards in the industry to improve air quality on construction sites.

We’ve set ambitious targets for our supply chain to minimise emissions, and to develop best practice solutions that can drive down emissions across the whole construction industry.

We are:

  • Changing industry Best Practice – The Institute of Air Quality Management Guidance on Monitoring in the vicinity of Demolition and Construction Sites (October 2018) was updated following the our study with Kings College London to evaluate construction site monitoring strategies. This study has resulted in an adjustment of the trigger alert level for PM10 as well as a set of quality assurance measures that should be implemented across construction sites.
  •  Developing Non-Road Mobile Machinery (NRMM) low emission technology to reduce our environmental impact. The NRMM retrofit could, once the research is completed, add technology to existing exhaust and engine systems to reduce emissions and recertify them as a newer engine class.
  •  Trialling the replacement of diesel power equipment with ultra-low emission engines on our sites. The project is funded by Innovate UK. The system offers hybrid and heat recovery technology along with real time measurements compared to equivalent diesel engines.
  • Leading the way with clean air measures by adopting a new plant emissions scheme, working with the Construction Equipment Association. HS2 has supported the development and adoption of the Non-Road Mobile Machinery (NRMM) Emission Compliance Verification Scheme as part of a bid to create greener construction sites.

Case studies

CESAR ECV - Construction Equipment Emissions Compliance Verification Scheme

HS2 has played a key role in helping the Construction Equipment Association (CEA) to develop the Emissions Compliance Verification (ECV) scheme and is now encouraging the industry to get on board. The ECV system fits with HS2’s Air Quality Strategy, which sets strict emission requirements for both on- and off-road vehicles and plant.

The new CESAR ECV system is a bolt-on’product, complimenting the existing CESAR security system, which allows quick and easy verification of a machine’s emissions category and helps ensure that emissions from plant is reduced where it cannot be avoided.

A unique colour-coded label fitted to each machine carries a QR code that provides full emissions data, bringing major time and cost savings, better reliability, and giving assurance to local authorities and the public that the strict emission requirements are being met, which is of particular importance on high-profile projects such as HS2.

There are also significant health and safety benefits using the CESAR ECV scheme, which allows for quick confirmation of a machine’s emissions by sight, whereas previously an operative had to look under the bonnet to find the engine plate to confirm compliance. During site inspection audits, where machinery is in use, this currently means that the machine has to be stopped and cooled, before an inspector can confirm its compliance, which involves costly down-time.

HS2 is currently recommending the use of the scheme to contractors and supply chains across the project, and a number of contractors are already talking to the CEA about adopting the new scheme.

HS2’s Air Quality Lead, Andrea Davidson says:

As the country’s largest infrastructure project, we have an opportunity to work with our partners and supply chain to create a greener way of designing and building the new railway. Environmental innovations are at the heart of everything we do – from reducing carbon emissions and using renewable energy on sites; to including eco-friendly features in our designs, creating hundreds of new wildlife habitats along the route, and helping Britain reach our 2050 net zero carbon emissions target.

It’s also important for us to provide assurances to local authorities and the public that we’re reducing emissions, tightly monitoring air quality and maintaining national air quality standards. The CESAR ECV system is one of many innovations we are supporting, and it’s now our job to embed it in the industry by encouraging our suppliers to use the new scheme as a tool for compliance assurance across all our sites.

Find out more about the ECV scheme.

Energy Alternatives

We are deploying and trialling lower emitting alternatives, such as hybrid, electric, renewable energy alternatives and hydrogen fuel cell technology across our sites.

In a major step towards greener construction sites, HS2 has trialled solar and hydrogen powered welfare cabins across construction sites, already cutting over 100 tonnes of carbon.
HS2’s Environment Director Peter Miller says:

HS2 is supporting the UK’s green economic recovery and ensuring the UK is on track to achieve its commitment to reach net zero carbon emissions by 2050. We aim to dramatically cut carbon on our construction sites, and constantly challenge our supply chain to introduce innovations by using the latest green technology.

With over 250 active work sites between London and Birmingham, we have a huge opportunity to roll out British-made products such as this solar powered cabin, to dramatically reduce the project’s carbon footprint, bringing environmental benefits to local communities as we build the railway.

Find out more about the trial.

Electric construction plant equipment

HS2 is pioneering the UK’s first electric telehandler on one of its major construction sites in London. With zero pollution, the Eco Telehandler vehicle has been trialled on HS2’s site at West Ruislip by main works civils contractor Skanska Costain STRABAG Joint Venture. It’s estimated that over a week, it saved over 400 litres of fuel compared to a traditional combustion telehandler.

By cutting pollution from emissions completely, it creates greener construction sites, improving air quality for workers and the local community. It also represents a significant fuel, carbon and cost saving, with fewer refuelling vehicles resulting in a reduction of plant movement, an improvement in safety for everyone on site.

Manufactured by Faresin and supplied by plant hire company Flannery, the environmentally friendly electric drive unit provides the same performance as an equivalent conventional model but without the noise and emissions of a combustion engine. It delivers a range of further benefits including reduced charging times and notable savings in maintenance when compared to a combustion engine telehandler.

Find out more about the trial.

Clean Air Gas Engine technology

In its bid to cut carbon and focus on improving local air quality, HS2 is trialing new ultra-clean generator technology developed by a collaboration of three UK technology companies. By replacing diesel with LPG, the innovation is set to cut carbon, lower emissions, reduce noise and deliver major cost savings.

OakTec Power Ltd has collaborated with generator manufacturer Sutton Power Engineering and site welfare specialist Advanté to develop the low emission, off-grid, electricity generation solution into a welfare cabin specifically designed for the needs of HS2 construction and its maintenance contractors. It is a hybrid energy system which utilises battery energy storage with solar panels to boost charging.

Find out more.

Non-Road Mobile Machinery retrofit

HS2’s Non-Road Mobile Machinery  retrofit innovation adds exhaust technology to existing engine systems on plant machinery to upgrade them to the latest EU Stage V engine class, leading to cleaner air around construction sites.

The six-month pilot of the retrofit solution was carried out by UK company Eminox on a Balfour Beatty Stage IIIA piling rig (Junttan PM20). It was tested by Imperial College London (Centre for Low Emission Construction) and Emissions Analytics, and has just been validated by the Energy Saving Trust, providing certainty for the sector and making it available industry-wide.

Find out more.

Assurance and further information

Quality assurance

HS2 Ltd has been recognised for its plans to minimise the project’s environmental impact. We were awarded an ISO 14001 certificate from Lloyd’s Register of Quality Assurance for our work in areas such as carbon emissions, air and water quality, biodiversity and waste.

Air Quality Strategy

This document sets out the strategy by which High Speed Two (HS2) will meets its sustainability policy with respect to air quality. The document is a guide to the relevant air quality policy and legislation, and the potential impacts of the scheme.

It sets out our approach to avoid, reduce and mitigate emissions, and how ‘best practicable means’ can be determined. This includes measures to control dust during construction, and how emissions associated with construction vehicles and machinery will be managed.

Environmental statements & Information Papers

HS2 Phase One environmental statement volume 3: route-wide effects

Chapter 4 of the Phase One Environmental Statement (2013) presents the assessment of the Air Quality of the Proposed Scheme during construction and operation.

Phase One Air Quality Information Paper

This paper outlines the carbon footprint and greenhouse gas assessment for HS2 Phase One.

Environmental Minimum Requirements  The Code of Construction Practice also has information on carbon and climate change adaptation and resilience.

HS2 Phase 2a environmental statement volume 3: route-wide effects

Chapter 3 of the Phase 2a Environmental Statement (2017) presents the assessment of the Air Quality of the Proposed Scheme during construction and operation.

Phase 2a Air Quality Information Paper

This paper outlines the carbon footprint and greenhouse gas assessment for HS2 Phase 2a.