The South Coast Air Quality Management District has responsibility to control air pollution. It can seek court-imposed fines against polluters of $25 to $25,000 a day based on such factors as the extent that emissions exceed legal limits, potential danger to the public, whether the violation was intentional, accidental or caused by negligence and the company's history of violations. These are the eight companies that incurred violations resulting in penalties of $2,500 or greater in January: COMPANY: Union Pacific Railroad Co., San Bernardino, Colton, Devore TYPE OF BUSINESS: Railroad PENALTY: $80,000 VIOLATION: Excessive smoke emissions from diesel engines. The company will spend an additional $215,000 to implement a compliance reporting program that outlines maintenance procedures to ensure the company's compliance with air pollution control rules. *COMPANY: AT&T; Communications, Mission Viejo, Irvine TYPE OF BUSINESS: Telephone company PENALTY: $31,000 VIOLATION: Failure to submit revised ride-sharing plans, failure to implement ride-sharing incentives listed in approved plans. The company also spent an additional $22,567 conducting an internal audit of the ride-sharing plans for all its facilities and on installing a new transportation management team. *COMPANY: International Permalite Inc., Ontario TYPE OF BUSINESS: Roofing board maker PENALTY: $20,000 VIOLATION: Releasing excessive amounts of dust, violating its permit to operate rule. *COMPANY: Unocal Corp., Wilmington TYPE OF BUSINESS: Refinery PENALTY: $10,000 VIOLATION: Public nuisance violation from a vapor cloud, excessive sulfur dioxide emissions from its sulfuric acid plant. *COMPANY: Robertshaw Controls Co., Long Beach TYPE OF BUSINESS: Space heater controls maker PENALTY: $6,500 VIOLATION: Excessive volatile organic compound emissions from a solvent. *COMPANY: Riverside County Publishing, Riverside TYPE OF BUSINESS: Publishing firm PENALTY: $6,000 VIOLATION: Operating an after-burner contrary to permit conditions, excessive volatile organic compound emissions from a printing ink. The company will spend an additional $5,000 retrofitting two delivery vehicles for propane fuel. *COMPANY: Shell Oil Co., Carson TYPE OF BUSINESS: Refinery PENALTY: $5,750 VIOLATION: Operating malfunctioning equipment contrary to permit requirements, excessive volatile organic compound emissions. *COMPANY: Western Dyeing & Finishing Corp.,Rancho Dominguez TYPE OF BUSINESS: Carpet dyers PENALTY: $2,600 VIOLATION: Failure to install low nitrogen oxide burners in its boilers.