Definitions
2.—(1) 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 Department considers that the need for ambient air be assessed or managed is justified;
“alert threshold” has the meaning given by Regulation 9(3);
“ambient air” means outdoor air in the troposphere, excluding workplaces;
“assessment” means any method used to measure, calculate, predict or estimate the level of ozone precursor substances in 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 9(3);
“level” means the concentration of ozone precursor substances in ambient air;
“long-term objective” has the meaning given in Regulation 4;
“ozone precursor substances” means substances which contribute to the formation of ground-level ozone, including those listed in Schedule 4;
“public” has the meaning given in Regulation 8(6);
“rural background station” has the meaning given by Part I of Schedule 2;
“target value” has the meaning given by Regulation 3;
“volatile organic compounds” or “VOCs” means all organic compounds from anthropogenic and biogenic sources, other than methane, that are capable of producing photochemical oxidants by reactions with nitrogen oxides in the presence of sunlight;
“the Department” means the Department of the Environment; and
“zone” means an area within Northern Ireland which is designated for the purposes of these Regulations and shown on a map published by the Department, the Scottish Executive, the National Assembly for Wales, and the Department for Environment, Food and Rural Affairs in January 2001, a copy of which is deposited at the offices of the Department, Calvert House, 23 Castle Place, Belfast, BT1 1FY.