The Air Quality Limit Values Regulations 2003

Definitions

2.  In these Regulations—

“agglomeration” means a zone with a population concentration in excess of 250,000 inhabitants, or, where the population concentration is 250,000 inhabitants or less, a population density per km² for which the Secretary of State considers that the need for ambient air to be assessed or managed is justified;

“alert threshold” has the meaning given in regulations 10(2) and (3);

“ambient air” means outdoor air in the troposphere, excluding work places;

“assessment” means any method used to measure, calculate, predict or estimate the level of a relevant pollutant, ozone or ozone precursor substances in the ambient air;

“fixed measurements” means measurements taken at fixed sites either continuously or by random sampling, the number of measurements being sufficiently large to enable the levels observed to be determined;

“information threshold” has the meaning given in regulation 10(3);

“level” means the concentration of a relevant pollutant, ozone or ozone precursor substances in ambient air;

“limit value” has the meaning given in regulation 4(1);

“long-term objective” has the meaning given in regulation 5(3);

“lower assessment threshold” has the meaning given in regulation 7(8);

“natural events” means volcanic eruptions, seismic activities, geothermal activities, wild-land fires, high-wind events or the atmospheric resuspension or transport of natural particles from dry regions;

“oxides of nitrogen” means the sum of nitric oxide and nitrogen dioxide added as parts per billion and expressed as nitrogen dioxide in microgrammes per cubic metre;

“ozone precursor substances” means substances which contribute to the formation of ground level ozone, including those listed in Schedule 6;

“PM_2.5” means particulate matter which passes through a size-selective inlet with a 50% efficiency cut-off at 2.5 µm aerodynamic diameter;

“PM₁₀” means particulate matter which passes through a size-selective inlet with a 50% efficiency cut-off at 10 µm aerodynamic diameter;

“public” has the meaning given in regulation 16(15);

“relevant pollutants” means sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter, lead, benzene and carbon monoxide;

“rural background station” shall be interpreted in accordance with Part II of Schedule 4;

“target value” has the meaning given in regulation 5(2);

“upper assessment threshold” has the meaning given in regulation 7(8);

“volatile organic compounds” or “VOC” means all organic compounds from anthropogenic and biogenic sources, other than methane, that are capable of producing photochemical oxidants by reaction with nitrogen oxides in the presence of sunlight; and

“zone” means a part of the territory of England shown on a map published by the Secretary of State on 19th January 2001, deposited at the offices of the Department for Environment, Food and Rural Affairs, Ashdown House, 123 Victoria Street, London SW1E 6DE and displayed on the Department’s website at http://www.defra.gov.uk/environment.