What do the World Health Organization (WHO) Air Quality guidelines have to do with London’s air?
The WHO is an organisation of 194 Member States committed to improving global health. The WHO publishes guidelines on many aspects of health, and air quality is one of these. The WHO states, “clean air is a basic human right” and their first air quality guidelines were published in 1987.
These guidelines cover several pollutants, ozone(O3), nitrogen dioxide (NO2), sulphur dioxide (SO2), carbon monoxide (CO), coarse particulate matter (PM10) and fine particulate matter (PM2.5). Here we will concentrate on PM2.5. The current version of these guidelines was published in 2021 with a new PM2.5 target of 5 μg/m3, down from 10 μg/m3 in 2005. Each of the countries that are members of the WHO will decide when, how, or even if, to incorporate this guideline into national or local legislation.
In England the Environment Act 2021 set out a new environmental framework and the Environmental Targets (Fine Particulate Matter) (England) Regulations 2023 sets the targets as a national level. This sets the annual mean PM2.5 target as 10 μg/m3 and that the population exposure to PM2.5 to be reduced by 35% compared to 2018 levels.
Progress towards these targets is measured at different locations across the country via the Automatic Urban and Rural Network (AURN) and, at February 2024, there are 175 monitoring sites and data is readily available on all of them. Below is the data from the AURN sites in London.
Many parts of England are looking at ways to improve on these environmental targets and meet the more stringent WHO guidelines.
In London there has been a commitment to meet the WHO targets since 2017. The London Environment Strategy sets out targets and plans for improving our environment in many ways, including air quality, climate change and waste management. The strategy was developed in 2017, consulted on publicly, and has been implemented from 2018 to 2023. At this time the WHO guideline was 10 μg/m3 and a roadmap to reach this target was published in October 2019. The WHO guideline is now 5 μg/m3 and the Mayor of London has presented his vision for London to have the best air quality of any major world city by 2050.
The measurements taken in London show that the annual average PM2.5 reduced from 13.0 μg/m3 in 2016 to 11.6 μg/m3 in 2019 from the 16 monitoring stations that captured data over that period. The latest LAEI modelling using data from 2019 showed that many or most parts of London are likely to be able to achieve the old annual average target of less than 10 μg/m3 by 2030, but when and how can we meet the new WHO target of 5 μg/m3?
A significant amount of the PM2.5 air pollution in London comes from outside sources and reducing these will involve national and international cooperation. The sources of PM2.5 air pollution that are generated inside London include:
- Domestic biomass and wood burning
- Commercial cooking
- Construction
- Industrial heating and processing
- Transport
The Clean Air Act, Low Emission Zone, Ultra Low Emission Zone, and Non-Road Mobile Machinery Low Emission Zone are all working to reduce the levels of PM2.5 in the air in London but we still have quite a lot of work to do before we get to the WHO target of 5 μg/m3.
We can each take action to improve air quality in our homes and neighbourhoods by reducing or eliminating our contributions to air pollution. There are many other actions that may be undertaken by local and central government on our behalf. One thing that we can all do is take part in the consultation for the next London Environment Strategy.
