In our campaign we state that domestic combustion is the second largest source of small particle (PM2.5) pollution in London, in this article we will look at the other sources of PM2.5 and what is being done to address them.

When looking at sources of PM2.5 we have to remember that not all of the PM2.5 in the air in London is produced in London. In turn, PM2.5 produced here is spread to other cities, towns and villages. Additionally some sources are natural such as sea spray and pollen. Below we are using the London Atmospheric Emissions Inventory (LAEI) 2019 as the source of data for this article as this is the most comprehensive source of atmospheric emissions data that we have available for London.

Road Transport

Road transport is the largest single source of PM2.5 in London. There are over 1,000 tonnes of PM2.5 being emitted by cars, trucks, buses and other vehicles every year from exhaust as well as from brake and tyre wear. The LAEI data above are from 2019, after the introduction of the Low Emission Zone (LEZ) and in the first year of the Ultra Low Emission Zone (ULEZ). There are a number of ways that the PM2.5 pollution from road transport is being reduced, as electric vehicles don’t produce polluting exhaust. Low emission zones, the rise of car clubs, cargo bike hire and the promotion of active travel are all changing the way that we travel and promoting a shift to forms of travel that produce less PM2.5.

Domestic Wood Burning

The 17% of PM2.5 emissions in London that is attributed to domestic wood burning comes from the wood burned in the homes of London residents and includes open fires and all types of wood burning stoves.  The LAEI is an inventory of emissions and does not have the capability to determine how much of this is produced by each different type of appliance. In the London Wood Burning Project (LWBP) Survey in 2022 we found that 12% of respondents had a useable open fireplace and 9% had a solid fuel burning stove. Of these 72% used their open fireplace at least once a month and 94% their solid fuel burning stove during winter. 10-15% of our respondents used coal some of the time and those emissions are shown in the Domestic Heat/Power section below.  Most homes have heating that does not involve combustion and can use these to avoid burning at home.

Commercial Cooking

Commercial cooking contributes an estimated 15% of the PM2.5 emissions in London. If this seems high it is worth noting that there are venues that are open, with grills and deep fat fryers running, for 24 hours a day, every day of the year and a wide variety of food vendors use charcoal or wood fires for cooking. The PM2.5 from cooking can be from the fuel used such as charcoal, wood, or a smaller amount from gas, or it can be produced by the frying and grilling of the food. Street vendors often use diesel generators to provide the power for cooking foods or keeping ingredients refrigerated. The pollution from commercial cooking can be a health risk to those working in kitchens, customers, and neighbours. There are already restrictions in place regarding pizza ovens in smoke control areas and planning conditions for commercial cooking may include filtration of wood and charcoal burning appliances. As the third highest single source of PM2.5 in London commercial cooking is an area of focus for many local authorities and there are already projects underway making electrical power available to ice cream vans and street food markets.

Construction

The PM2.5 emitted by the construction industry is predominantly demolition and construction dust. Each local authority works closely with developers to control dust and emissions during any demolition or construction activity. The levels of pollutants emitted from construction sites are monitored during all phases of the construction project.

About 10% of the PM2.5 from construction is from Non Road Mobile Machinery (NRMM) and this is being reduced by the NRMM Low Emission Zone.

Domestic Heat/Power

This is the PM2.5 from the domestic burning of gas, oil, and coal. The contribution of coal to pollution in London will have reduced since 2019 due to the ban on the sale of household coal in England.

Industrial Processes

This includes the emissions from NRMM in industrial settings and particulate matter produced from industry that is not filtered or removed from air circulation in industrial buildings.

Industrial Heat/Power

This is the PM2.5 from the industrial burning of gas, oil and coal for industrial heat and power. Industrial heat and power sources are moving to electrification, and this will lead to a reduction in PM2.5 emissions.

Other

This includes small contributors to PM2.5 in London such as accidental fires, agriculture, forestry and garden machinery. There isn’t a lot of agriculture and forestry undertaken in London and the trend in garden machinery is away from petrol powered sources and towards electrically powered garden equipment.

Aviation

Aviation only contributes 2% of the PM2.5 in London and this seems surprising at first. While the United Kingdom, and especially the south-east, has a lot of air traffic there are very few airports, airfields, and heliports in London.

Resuspension

Resuspension refers to material that had been deposited from the air going back into the air. This can be PM2.5 blown back up by the wind, traffic or any movement that scrapes particles up from the ground or other surfaces. If fewer particles are emitted, then fewer particles are available for resuspension and this emissions source should reduce along with reductions in emissions.

Air Quality Management

Each local authority in London is working to improve air quality in their borough and, by extension, across London as a whole. The statutory duty to monitor air quality provides comprehensive data for local and national reporting. Read our article on meeting World Health Organization guidelines for more information on this monitoring. The council will declare an Air Quality Management Area (AQMA) in any areas where air quality targets are unlikely to be met. Once this AQMA is in place there will be an Air Quality Action Plan drafted to change this and focus attention so that air quality targets are able to be reached. See if your local authority has any AQMAs and the action plans in place to meet planned air quality targets in your local area.