New findings from the Imperial College London estimate that air pollution causes heart attacks, strokes, and lung disease that kill over 30,000 Americans each year, which is about the same number of deaths from car accidents each year.
The study, published last week in the journal PLOS Medicine, found a connection between cardio-respiratory and excess particulate matter pollution, known as PM2.5, is about 30 times smaller than the width of a human hair -- comes from automotive, power generation, and industrial engines.
Millions of Americans are inhaling PM2.5 daily, which build up in small blood vessels in the lungs, and over an extended period, can cause lung disease. These dangerous particles also are absorbed into the bloodstream that can increase the risk of heart disease, the researchers suggested.
Researchers noted that PM2.5 levels have dropped in the last two decades, but in some areas around the country - the levels remain seriously high.
Los Angeles remained one of the worst cities for PM2.5 along with several regions in Arkansas, Oklahoma, and Alabama.
Inner cities deemed low-income areas across the US also had dangerous levels of PM2.5.
Researchers said this "inequality in mortality burden" occurred because of the low-income population was already prone to higher rates of preexisting medical conditions.
"I think the big conclusion is that lowering the limits of air pollution could delay in the US, all together, tens of thousands of deaths each year," Majid Ezzati, the study's lead author and a professor of global environmental health told CNN.
Air quality data between 1999 and 2015 at over 750 monitoring stations across the US were cross-referenced with death records for cardiovascular-related diseases to determine the dangers of PM2.5, the researchers noted.
The governments acceptable PM2.5 level is 12 micrograms per cubic meter of air (ug/m3).
In 1999, Fresno County, California, recorded 22.1 ug/m3; by 2015, the level was at 13.2 ug/m3 for Tulare County, a region 20 miles from Fresno.
In the last several years, the Trump administration has rolled back a wide variety of regulations that protect the air we breathe.