Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, for what reasons the Clean Air Strategy 2018 does not discuss PM1 and PM0.1; and what evidence his Department has on the safety to human health of (a) those particles and (b) urban air quality.

The Clean Air Strategy 2019 sets out our proposals for meeting our legally binding emissions ceilings for five key pollutants – fine particulate matter (PM_2.5), nitrogen oxides (NO_x), sulphur dioxide (SO₂), ammonia (NH₃) and non-methane volatile organic compounds.

The pollutant with the strongest evidence for impacts on human health is PM_2.5. Many of the sources of PM_2.5 are also responsible for PM₁ and PM_0.1, and so our actions to reduce emissions of fine particulate matter will have positive benefits for the emissions of even smaller particles. The other four pollutants also often undergo chemical reactions in the air, becoming PM₁ or PM_0.1 particles. The reductions in the emissions of these pollutants will result in less pollution to undergo these reactions, and therefore fewer PM₁ or PM_0.1 particles formed in the air.

a) While we have not made an assessment of the impact on health of PM₁, the independent Air Quality Expert Group published a report into PM_0.1 particles (known as ultrafine particulate matter) which is available on Defra’s UK-AIR website.

b) Defra does not report on the health effects of urban air quality specifically, but we do carry out assessments of air quality nationally. The quality of our air is improving nationwide, with lower emissions and lower concentrations, and much of the decrease in emissions has been in urban areas. Our Clean Air Strategy is emission-source focused, and as urban areas are often where there are most sources, these are the areas that will experience the biggest benefits from the Strategy.