Group 1 - The article discusses the obligation to pay environmental protection tax for entities that discharge taxable pollutants, with exemptions for those meeting national and local discharge standards [3] - It defines urban sewage treatment facilities as those providing public sewage treatment services, excluding those serving industrial zones [3] - Entities discharging taxable pollutants to legally established centralized sewage treatment or waste disposal sites are not required to pay the environmental protection tax [4] Group 2 - The term "pollution equivalent" is explained as a comprehensive indicator or measurement unit that assesses the harmful degree of pollutants or pollution discharge activities on the environment [5] - The calculation of taxable pollutant emissions is detailed, including methods based on automatic monitoring data, third-party monitoring data, and other prescribed calculation methods [6] Group 3 - The article emphasizes that self-monitoring data for pollutants may not be accepted as a basis for calculating pollutant emissions [7]