Portaria n. 286/93 de 12/03/1993. Fixa os valores limites e os valores guias no ambiente para o dióxido de enxofre, partículas em suspensão, dióxido de azoto e monóxido de carbono, o valor limite para o chumbo e os valores guias para o ozono. Diário da República I Série B n. 60 de 12/03/1993 Página 1169

This Portuguese regulation establishes legal limit values and target levels for several key air pollutants, including sulfur dioxide, nitrogen dioxide, carbon monoxide, lead, and ozone. Its purpose is to monitor and control air pollution to protect public health and the environment. This affects industrial operators and public authorities responsible for environmental monitoring. It sets the thresholds that must not be exceeded to ensure air quality meets safety standards.