The U.S. Environmental Protection Agency announced proposed new regulations Thursday that would further reduce legal limits for fine particle pollution -- otherwise known as soot -- in the nation's air. Gina McCarthy, assistant administrator for the EPA's Office of Air and Radiation, made the announcement in a phone call with reporters, saying that the new standard would save thousands of lives and an upward estimate of billions of dollars in healthcare costs. The EPA was under a court order, issued earlier this month, to propose new standards for fine particulate matter under 2.5 micrometers, or PM2.5 as it's called, according to the best available science by Thursday. The proposed regulations would reduce the acceptable amount of soot in the air from the current standard of 15 micrograms per cubic meter of air to a level between 12 and 13 micrograms per cubic meter. This soot comes from varied sources such as power plants, diesel engines and wood fires. The proposed standards will go through a nine-week comment process and must be finalized by Dec. 14. "The good news about today's actions is that we're already on the path for 99% of U.S. counties to meet the proposed standards without the need for additional state or local action," said McCarthy on Thursday. She went on to explain that regulations and programs already in place are projected to bring soot levels down under 12 micrograms by the year 2020 in all but six counties nationwide, according to EPA projections. Several of these programs, however, including the recently announced Mercury and Air Toxic Standards, or MATS, are being challenged in court. Updating these standards will protect us from the tiniest particles that can cause the biggest health problems. By limiting the smoke, soot, metals and other pollution our lungs and hearts absorb, EPA is protecting all of us from asthma attacks, lung cancer, heart disease and premature deaths," said John Walke, clean air director at the Natural Resources Defense Council, in a statement. But not all environmentalists or trade groups were satisified with the news. "EPA's proposal could substantially increase costs to states, municipalities, businesses and ultimately consumers without justified benefits," said Howard Feldman, director of regulatory and scientific affairs at the American Petroleum Institute, in a statement. He went on to explain that companies will be reluctant to invest or build new plants or refineries in counties that cannot meet the new standards, thus taking an economic toll. McCarthy disagreed, saying, "In those few areas with specific, localized challenges, like old diesel engines around ports, railyards or roadways or whether it's wood stoves in valleys, EPA will partner with those communities by providing technical assistance or other voluntary initiatives - like our DERA (Diesel Emmisions Reduction Act, which provides funds for clean diesel conversion) program - to help them to achieve clean air standards that others will be enjoying." The six counties currently listed as projected to fail the new standard by 2020 include Riverside and San Bernardino counties in California; Santa Cruz, Arizona; Wayne, Michigan; Jefferson, Alabama; and Lincoln in Montana. Conrad Schneider, advocacy director at a group called Clean Air Task Force (CATF), sent an emailed statement hailing the new proposed standards, but saying the group would urge EPA to take it down yet another notch to 11 micrograms/m3. "According to our "Sick of Soot" report, jointly released with the American Lung Assn. and Earthjustice, setting the annual standard at 11 micrograms/m3 would save an estimated 27,000 American lives more than under the current standard, and fully 12,000 more lives would be saved than setting a level of 12 micrograms/m3." The EPA was required under the Clean Air Act to review its standards in light of the latest scientific evidence. In 2006, the Bush administration issued PM2.5 limits that were eventually rejected by federal courts in 2009 for failing to protect public health, and a court ruling earlier in June required the EPA to sign off on new proposed rules. "A strong body of science, which includes hundreds of new studies, shows fine particles harm health," said McCarthy. Particles smaller than 2.5 micrograms, which we call PM2.5, can penetrate deep into the lungs to cause premature death. This pollutant is also linked to a wide variety of serious health effects, including heart attack, strokes, aggrevated asthma, and increased hospital admissions and emergency room visits. Exposure to particle pollution is estmated to cause tens of thousands of premature deaths each year. The EPA estimates that the cost of implementing the new standards would range from $2.9 million to $69 million, with savings in health costs estimated from $88 million to $5.9 billion. McCarthy also noted that regulations regarding visibility, or haze, and course particulate matter called PM10 would remain unchanged. Diesel exhaust can cause cancer, World Health Organization says Global warming could lead to more wildfire in California: study