Air Quality

NO₂ primarily gets in the air from the burning of fuel. NO₂ forms from emissions from cars, trucks and buses, power plants, and off-road equipment.

Concentrations of NO2 @ gov.uk

Ground level ozone(O3), is not emitted directly into the air, but is created by chemical reactions. This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight.

The Air Quality Standards Regulations 2010 set the target that that a three-year average of 8-hour mean concentrations of O3 should not exceed 120 µg/m³ more than 25 times.

Concentrations of ozone @ gov.uk

Nitrogen oxides (NO) are produced from fuel combustion in mobile and stationary sources. The combustion of fuel in car emit nitrogen oxides into the atmosphere (mobile source). Stationary emissions come from coal fired power plants, electric power plant boilers.

PM_2.5 particles are invisible to the naked eye and small enough to pass through the lungs, into the bloodstream, and into your organs. Generally, they come from the combustion of solid and liquid fuels, through power generation, domestic heating and in-vehicle engines.

Concentrations of PM2.5 and PM10 @ gov.uk

PM10 is any particulate matter in the air that include including smoke, dust, soot, salts, acids, and metals. Particulate matter can also be formed indirectly when gases emitted from motor vehicles and industries undergo chemical reactions in the atmosphere or other sources such as or domestic fireplaces

What the weather is doing can have direct effects on air quality at a given location. For example, sunshine, rain, air temperature and wind can affect the amount of air pollution present:

• Sunshine - makes some pollutants undergo chemical reactions, producing smog.

• Rain - washes out water-soluble pollutants and particulate matter.

• Higher air temperatures - speed up chemical reactions in the air.

• Wind speed, atmospheric turbulence/stability, and mixing depth - affect the dispersal and dilution of pollutants.

The PM2.5 Annual Mean Concentration target for 2040 will be 10 µg m-3. The UK Government will set some interim targets to achieve this. The first will be published in January 2023 (Red line indicates the 2040 target)