Supporters of the EPA’s action emphasized the economic benefits to businesses and relief from regulatory burdens.

Combined emissions of the six common air pollutants declined by 74% from 1970 to 2018, according to the EPA, while the country’s economy increased 275%, said U.S. Rep. Buddy Carter, R-Ga., a member of the House Energy and Commerce Committee.

“What we’re doing is working,” he said, and retaining the current standards “will not only work to continue to improve our air quality, but it will also provide certainty to states, communities and businesses who must comply with these federal regulations in these extremely uncertain times.”

Over almost 30 years, the air quality in Georgia has improved. From 1990 to 2017, total emissions of the six key air pollutants dropped by 69%, according to data from the state Environmental Protection Division. But metro Atlanta is among the top 25 cities with the highest levels of year-round particle pollution. DeKalb, Fulton, Gwinnett and Henry counties each received a failing grade for the amount of ozone pollution levels in recent data from the 2019 American Lung Association "State of the Air" report. They are among the seven Georgia counties that remain in violation of federal standards for ozone levels, according to EPA tracking.

>> DEEPER FINDINGS: Five metro Atlanta counties earn a failing grade for air quality

The Harvard study, which was released publicly and is undergoing peer review, concluded that even a small increase in long-term exposure to PM2.5 leads to a large increase in the COVID-19 death rate. Researchers from the university's T.H. Chan School of Public Health analyzed data on COVID-19 deaths and levels of PM2.5 from more than 3,000 counties — including some in metro Atlanta — representing 98% of the U.S. population. Counties that averaged just 1 microgram per cubic meter more PM2.5 in the air had a 15% increase in the COVID-19 death rate.

In Manhattan, the current epicenter of the pandemic, lowering the long-term average PM2.5 exposure by 1 microgram per cubic meter would have resulted in 248 fewer COVID-19 deaths among a total of 1,905 deaths through April 4, wrote study researchers.

“We will probably see more studies around this, but we have known for a long time that long-term exposure to particulate pollution worsens symptoms of lung disease, increases susceptibility to lung infections, triggers heart attack and stroke and in some cases can cause lung cancer and premature death,” said June Deen, senior director, advocacy for the American Lung Association. She said the study data would be helpful in informing immediate decisions about how to best allocate medical resources during the COVID-19 pandemic.

With the debate around air pollution and COVID-19 likely to continue as the EPA proposal undergoes a 60-day public comment period, there are also lessons to take from the improved air quality that has resulted from shelter-in-place orders in many major cities. When Gov. Brian Kemp issued a state of emergency on March 14, much of the metro area shut down. Everyone except essential workers was asked to remain at home, which resulted in many employees working remotely.

Limited air travel, fewer cars on the road and reduced energy consumption may have helped reduce overall levels of PM2.5 and harmful nitrogen dioxide (NO2), produced by vehicles, power plants and industry. The impact is extreme in countries like India and China, which have the worst pollution levels in the world, but even in the U.S., the air looks a bit cleaner.

A satellite image shows levels of NO2 in the metro Atlanta area from March 11 - 31, 2019. Credit: Descartes Labs

Satellite images showing levels of NO2 over metro Atlanta from March 11 - 31, 2020. Credit: Descartes Labs

Data from the European Space Agency’s Sentinel-5P satellite shows lower levels of NO2 across the metro Atlanta area from March 11-31 compared to the same time period in 2019. Though cloud cover and other factors that can alter data quality are filtered out of the composite images created by Descartes Labs, state meteorologist Bill Murphey said more data is needed, particularly in months when meteorological factors are likely to produce higher levels of pollution.

Hot, dry, sunny, stagnant days in the months ahead are most conducive to ozone formation, he said, not the wetter weather that the metro area has seen so far this year. Rain can also lower levels of PM2.5. “As far as our continuous monitoring for the ozone and PM2.5, those haven’t showed anything real substantial yet. It was hinting at a decline, but if you look at the meteorology, there would be that much anyway,” Murphey said.

But some emissions reductions have likely occurred. Air travel from Hartsfield-Jackson International Airport is a major contributor to NO2 in the air, and the reduction in flights may have helped bring a reduction in emissions, Murphey said.

It reminded Deen of a 2001 study on the 1996 Olympics when efforts to reduce traffic downtown led to a reduction in ozone pollution and resulted in significantly lower rates of childhood asthma events. Then, and with the Harvard study now, Deen felt it was an illuminating look at how air pollution can impact health.

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“We are always in public health having to point out how the impact of the world around us may affect our health adversely,” Deen said. “The 1996 study was an opportunity to point to how correcting transportation patterns produced benefits to public health.”

Deen is concerned that recent policy decisions are being proposed without a thorough review of scientific research and concern for public health. “When we come out of this, we need to know the ways we can make public health stronger,” she said. “If there has ever been a time when science is important, it is now.”

REDUCTIONS OVER TIME

In 1970, Congress established the National Ambient Air Quality Standards (NAAQS), which set maximum allowable concentrations of particulate matter and other pollutants. The Environmental Protection Agency was created to enforce those regulations in partnership with state, local and tribal authorities. Regulations and standards are updated to reflect changes in technology and our understanding of what levels of pollutants are safe. Americans now enjoy 62% less pollution and 1.5 more years of life since 1970. Here is a look at air quality trends in Georgia from 1990-2017 for the six key air pollutants:

Carbon monoxide — down 69%

— down 69% Nitrogen oxide — down 60%

— down 60% PM2.5 (small particulate matter) — down 61%

— down 61% PM10 (larger particulate matter) — down 51%

— down 51% Sulfur dioxid e — down 95%

e — down 95% Volatile organic compounds — down 54%