These Regulations specify limit values in ambient air for 6 pollutants (SO2, NO2 and NOx, PM10, lead, benzene and CO) to come into effect in two stages. Alert thresholds for SO2 and NO2 are specified. The Regulations also specify margins of tolerance for exceedance of the new limit values in the period prior to their entry into force, which have relevance to the air quality assessment responsibilities assigned to the Environment Protection Agency in the Regulations. The Regulations provide for advice by the Agency to local authorities about the need for air quality management plans where the limit values, plus margins of tolerance, will be or may be exceeded, and the preparation of such plans by local authorities. Provision is also made for air pollution action plans for short-term risks of exceedances of the limit values and alert thresholds. The Regulations also provide for public information procedures, including where specified public alert thresholds are exceeded, to deal with incidences where there is a risk to human health from brief exposure of SO2 and NO2.