BP illegally emitted 500,000 pounds of air contaminants at its Texas City refinery over a recent 40-day period, and poor operating practices have caused 'egregious' pollution at the plant over much of the past decade, the state of Texas alleged in a lawsuit Monday. Attorney General Greg Abbott's office said it will seek civil penalties against BP Products North America, BP's refining division, for each violation of the state's air-quality laws - penalties that could reach into millions of dollars. And if the state prevails, it also could jeopardize BP's federal probation for a criminal conviction related to a deadly explosion at the plant five years ago, subjecting the company to further criminal prosecutions for previous offenses and bringing more government oversight to the refinery, said James Nebout, a Houston trial attorney who has sued BP multiple times. 'That has got to be BP's biggest worry right now,' Nebout said. Texas City residents have been on edge since word began to circulate last month that the company reported intentionally releasing pollutants from the country's third-largest oil refinery after a fire April 6. The blaze compromised a seal in a hydrogen compressor used in conjunction with the refinery's ultracracker. BP isn't accused of failing to disclose the unauthorized pollution release. Last week, before the state went to court, thousands of workers and residents signed up as plaintiffs in lawsuits alleging they were sickened by the prolonged exposure to the chemicals. Emissions included 17,000 pounds of the known carcinogen benzene, along with large amounts of carbon monoxide and nitrogen oxides. The new complaint by Abbott is the second the state has brought against the company in as many years and comes as the company faces billions in liabilities arising from the fatal Deepwater Horizon rig explosion and Gulf oil spill. The company said Monday it so far has spent $6.1 billion on spill cleanup efforts. BP spokesman Scott Dean said the company will continue to cooperate with the Attorney General's Office and the Texas Commission on Environmental Quality to resolve their concerns. BP maintains air-quality monitors did not show elevated readings or ground-level impact of benzene and other substances. But Neil Carman, an air-quality expert with the Sierra Club's Lone Star chapter, said the release was unusually large given that most unauthorized releases typically range from 5,000 to 10,000 pounds. 'Rarely do we see releases surpassing 100,000 pounds, let alone 500,000 pounds,' Carman said. History of violations In its complaint, the attorney general cites 15 of the same violations it did last year, when it alleged shoddy operations and maintenance practices at the plant led to a series of harmful releases between 2000 and 2007, including one linked to the March 2005 explosion that killed 15 workers. Monday's suit adds 39 other unauthorized pollution events to establish what it claims is a history of repeated violations and pattern of bad practices. The suit follows an investigation by the environmental commission, which cited the company for an 'excessive emissions event' following the April fire. The compressor was shut down and gases rerouted to a flare, which burned for 40 days. Chemicals also were released. BP told regulators that the fire likely was caused by liquids present in the compressor seal or by iron sulfide contamination and acknowledged that periodic equipment cleaning might have prevented the incident. The state's suit alleges that BP put profits over environmental compliance because it continued to run the ultracracker and other units while the compressor was out, allowing pollutants to escape. 'BP made very little attempt to minimize the emission of air contaminants caused by its actions,' the complaint reads. Compressor trouble The complaint also points out that the company has had previous trouble with the hydrogen compressor, saying the same equipment was involved in seven of 72 violations following the 2005 explosion. The Texas Commission on Environmental Quality said chemical concentrations in the air resulting from the April-May release did not exceed state or federal standards but that regulators could not determine the short-term health effects. Last week, Houston lawyer Tony Buzbee filed a $10 billion class-action lawsuit against the company alleging more than 2,000 people suffered health problems because of the incident. Chronicle reporter Matthew Tresaugue contributed to this report. monica.hatcher@chron.com XXX - End of Story3D 