A new study quantified the benefits of pollution reduction in terms of race and class.The Environmental Protection Agency is considering new standards for the maximum amount of fine particulate matter, tiny specks about one-thirtieth the diameter of a human hair that can penetrate the lungs, in outdoor air. A recent study examined how the benefits of stricter limits would be distributed across American society.What’s new in this researchImplementing stricter limits on fine particulate matter could reduce mortality rates by up to 7 percent for Black and low-income Americans over 65 who are already exposed to some of the dirtiest air in the United States, according to the study, led by researchers from the Harvard T.H. Chan School of Public Health.There is already overwhelming evidence that people of color, and Black communities in particular, are disproportionately exposed to harmful air pollutants like the fine particulate matter examined in the study, which is known as PM 2.5 because it is no more than 2.5 micrometers in diameter.The new research, published Friday in The New England Journal of Medicine, found that tightening the limit on fine particulate matter by 4 micrograms per cubic meter of air would result in a 4 percent reduction in the mortality rate for higher-income white adults. The same change would result in a reduction of 6 percent to 7  percent for higher-income Black adults, lower-income white adults and lower-income Black adults.“We need to look at the intersection of race and socioeconomic status to really understand how structural racism, differences in access to health care, and economic disparity play a role,” said Francesca Dominici, a biostatistics professor at Harvard and senior author on the study.Why this is importantThe new research could inform a crucial Environmental Protection Agency decision to tighten limits on fine particulate matter, including soot, which can come from construction sites, smokestacks, diesel trucks, power plants and other industrial activity. Wildfire smoke is also a major source of particulate matter pollution.In January, the E.P.A. proposed a draft rule that would tighten limits on fine particulate matter from the current standard of 12 micrograms per cubic meter to a level between 9 and 10 micrograms per cubic meter. The administration has estimated that the guidance could prevent as many as 4,200 premature deaths each year.However, some environmental justice advocates have said that the rule should strengthen the standard even more to protect the most vulnerable communities. The findings from the new research reveal that there are potentially “real, meaningful differences” between setting the limit at 10 micrograms versus a stricter 8 micrograms, said Scott Delaney, an author on the study and an epidemiologist at Harvard.There are likely tens of millions of Americans who live in communities with levels of PM 2.5 between 8 and 10 micrograms per cubic meter, said Joshua Apte, an associate professor of civil and environmental engineering at the University of California, Berkeley, who did not work on the study. “Those people could be left behind by the new standard.”The new rule, which will likely be finalized later this year after a period of public comment, is a central component of the Biden administration’s effort to address environmental justice, Michael Regan, the E.P.A. administrator, has said.Understand the bigger pictureIn a separate study last year, researchers uncovered stark disparities between white Americans and people of color across thousands of categories of pollution, including trucks, industry, agriculture and even restaurants.A study from 2020 quantified how air pollution ignores borders: In most states, about half of the premature deaths caused by poor air quality are linked to pollutants that blow in from other states.And policies made decades ago have been shown to have long-lasting effects. A study in March last year found that urban neighborhoods that were subject to redlining, the discriminatory practice of withholding banking and other services from nonwhite communities, in the 1930s tended to have higher levels of harmful air pollution eight decades later.

While the concentrations are low, the chemicals are potentially dangerous and some are linked to cancer risk, the researchers found.The natural gas delivered to homes contains low concentrations of several chemicals linked to cancer, a new study found. Researchers also found inconsistent levels of odorants — substances that give natural gas its characteristic “rotten egg” smell — which could increase the risk of small leaks going undetected.The study, which was published in the journal Environmental Science & Technology, adds to a growing body of research that links the delivery and use of natural gas to detrimental consequences for public health and the climate.Most prior research has documented the pollutants present where oil and gas extraction takes place, but there are “fewer studies as you work your way down the supply chain,” said Drew Michanowicz, the lead author of the study, looking at “where we actually use it, in our homes.”Over 16 months, researchers collected 234 samples of unburned natural gas from 69 homes in the Boston metropolitan area that received natural gas from three suppliers. They found 21 “air toxics” — an Environmental Protection Agency classification of hazardous pollutants known or suspected to cause cancer, birth defects or adverse environmental effects — including benzene, which was detected in 95 percent of the samples.Short-term exposure to high levels of benzene in particular could lead to drowsiness, dizziness, headaches and irritation of the eyes and skin, according to the Centers for Disease Control and Prevention. Longer-term exposure can increase the risk of blood disorders and certain cancers like leukemia.The highly flammable chemical is colorless or light yellow, and is found in products made from coal and oil including plastics, resins and nylon fibers, and also some types of rubbers, dyes and pesticides. It is also regularly found in vehicle exhaust, tobacco smoke and gasoline.The concentrations of benzene that the researchers found in the natural gas samples were “much lower compared to the amount in gasoline,” Dr. Michanowicz said on Friday during a conference call with reporters. Even so, he said, the finding is concerning since “natural gas is used so widely in society and in our indoor spaces.”Americans spend more than 90 percent of their time indoors, according to the E.P.A., where concentrations of some pollutants can range from two to five times as high as outdoor concentrations.Benzene is a carcinogen, and exposure over time adds up, leading some experts to suggest that there is no safe level of exposure.The researchers said that the goal of their study was to identify the presence and concentration of certain hazards, and that more research is needed to understand the health risks.“The largest sources of benzene in most people’s lives are gasoline from cars and smoking,” said Rob Jackson, an earth scientist at Stanford University who did not work on the study. “On the other hand, any unnecessary benzene in your home is just too much.”The unburned natural gas also contained inconsistent levels of odorants, or substances that give off a perceptible smell, the researchers said. Methane, the main component of natural gas, is odorless, so odorants are routinely added to help detect leaks.Understand the Latest News on Climate ChangeCard 1 of 5Logging.