A nonpartisan association that seeks to safeguard national parks in the U.S. is criticizing the U.S. Environmental Protection Agency’s proposal of new soot pollution standards, saying they don’t address ecosystems and overall welfare.

The National Parks Conservation Association, with more than 1.6 million members and supporters, said the proposed new standards don’t address the 24-hour standard and “do not properly address soot pollution’s resulting harms to nature, crops and other entities that affect public welfare” a news release said.

The proposed new “National Ambient Air Quality Standards” for fine particulate matter, known as “PM2.5,” would lower standards “to between 9-11 from 12 micrograms per cubic meter … for public health [‘primary standards’],” the release said. The new standards don’t address the 24-hour standard and “secondary standards” in regard to soot pollution harming nature, crops and more, the release said.

“The primary, health-based standards are meant to protect people, including our most vulnerable populations like children, the elderly, people of color and people with preexisting health conditions,” the release said. “Secondary effects pertain to animals and ecosystems, soil, water, crops, vegetation, property, weather, visibility, manmade structures and general quality of life, and there is abundant research showing that PM2.5 is detrimental to each.”

Ulla Reeves, campaigns director for the National Parks Conservation Association’s Clean Air Program, said in the release that the Biden administration took a “modest step toward cleaner air” that “doesn’t go far enough.”

“The science is clear, soot is bad for the health of our communities and national parks,” Reeves said. “Beyond the harm it causes people, soot wreaks havoc on our national parks’ plants, wildlife, waters and our views. EPA must set standards that match any strengthening of the public health standard to incrementally safeguard nature, our national parks and everything they protect.”

PM2.5 are tiny droplets in the air that are 2 1/2 microns or less in width (there are approximately 25,000 microns in an inch), the New York State Department of Health’s website said. The amount of PM2.5 over a 24-hour period determines health impact, the Indoor Air Hygiene Institute’s website said.

“The short-term standard [24-hour or daily average] is 35 micrograms per cubic meter of air [µg/m3] and the long-term standard [annual average] is 12 µg/m3,” the New York Health Department said. “A microgram is a unit of weight. There are a million micrograms in a gram, and a pound is equal to about 450 grams.”

The Indoor Air Hygiene Institute’s website said that PM2.5 at or below 12 μg/m3 is considered healthy.

“If the level goes to or above 35 μg/m3 during a 24-hour period, the air is considered unhealthy and can cause issues for people with existing breathing issues such as asthma,” the Indoor Air Hygiene Institute said. “Prolonged exposure to levels above 50 μg/m3 can lead to serious health issues and premature mortality.”

William Janeway, executive director of the Adirondack Council, said in the release that soot harms lungs and inhibits forest growth in Adirondack Park in New York and across the nation.

“Soot also worsens the impact of global warming by darkening ice and snow, causing them to melt faster in sunlight,” Janeway said. “We need strong soot emissions standards. Just as important is the need to invest in climate, clean water and clean air monitoring and research, so Northeast states can modernize their air-quality monitoring systems and can verify whether the standards are working.”