Air Pollution in Delaware: Philadelphia Metro Area Continues to Rank Among Worst 25 in Nation for Two Measures of Air Quality; County Grades in State Remain Unchanged, Finds 2020 ‘State of the Air’ Re

American Lung Association’s annual air quality report finds nearly half of Americans breathing unhealthy air

Editor’s Note: The full report, as well as UPDATED trend charts and rankings for metropolitan areas and county grades WILL BE available at beginning at 12:01 a.m. EDT April 21, 2020.

The American Lung Association’s 2020 “State of the Air” report found the Philadelphia-Reading-Camden, PA-NJ-DE-MD metro area, which includes Delaware’s New Castle and Kent Counties, ranked as the 12th most polluted city in the nation for its year-round average levels of fine particle pollution and as the 23rd most polluted for days with high levels of ozone smog. Ozone and particle pollution are the nation’s most widespread air pollutants, and both can be deadly. In contrast, the report found that Philadelphia’s measure for daily spikes of fine particle pollution improved to its best level ever.

The Lung Association’s annual air quality “report card” tracks Americans’ exposure to unhealthful levels of particle pollution and ozone during a three-year period. Once again, the report found that nearly half of all Americans were exposed to unhealthy air in 2016-2018. In Delaware, ozone air pollution placed the health of nearly a million residents at risk, including those who are more vulnerable to the effects of air pollution such as older adults, children and those with a lung disease.

“This year marks the 50th anniversary of the Clean Air Act, which has been responsible for dramatic improvements in air quality. However, Delaware residents continue to breathe some of the most unhealthy air in the country, driven by emissions from vehicles and industrial sources, both locally generated as well as significantly from upwind, placing their health and lives at risk,” said American Lung Association Chief Mission Officer Deborah Brown. “Furthermore, with nearly half of Americans breathing unhealthy air, our ‘State of the Air’ report shows that nationally, because of climate change, the nation is heading in the wrong direction when it comes to protecting public health.”

Each year the “State of the Air” provides a report card on the two most widespread outdoor air pollutants, ozone pollution, also known as smog, and particle pollution, also called soot. The report analyzes particle pollution in two ways: through average annual particle pollution levels and short-term spikes in particle pollution. Both ozone and particle pollution are dangerous to public health and can increase the risk of premature death and other serious health effects such as asthma attacks, cardiovascular damage, and developmental and reproductive harm. Particle pollution can also cause lung cancer, and new research links air pollution to the development of serious diseases, such as asthma and dementia.

This year’s report covers 2016, 2017 and 2018, the years with the most recent quality-assured data available collected by states, cities, counties, tribes and federal agencies. Notably, those three years were among the five hottest recorded in global history. Rising temperatures lead to increased levels of ozone pollution. Changing climate patterns also fuel wildfires and their dangerous smoke, which increase particle pollution. Ozone and particle pollution threaten everyone, especially children, older adults and people living with a lung disease. Although this report does not cover data from 2020, amid the COVID-19 pandemic, the impact of air pollution on lung health is of heightened concern. Learn more about that at

New Castle and Kent Counties fall into the 4-state, 16-county Philadelphia-Reading-Camden, PA-NJ-DE-MD metro area. And Sussex County is in the 2-state, 5-countySalisbury-Cambridge, MD-DE metro area. In addition to providing metro area rankings, the 20th annual “State of the Airreport also grades and ranks individual counties.

Ozone Pollution in Delaware

Compared to the 2019 report, Kent and Sussex Counties experienced more unhealthy days of high ozone in this year’s report, earning a “C” and a “D” respectively. New Castle County improved slightly but got an “F.” All grades remained unchanged in the 2020 report.

“Ozone pollution can harm even healthy people, but is particularly dangerous for children, older adults and people with lung diseases such as COPD or asthma,” said Brown. “Breathing ozone-polluted air can trigger asthma attacks in both adults and children with asthma, which can land them in the doctor’s office or the emergency room. Ozone can even shorten people’s lives.”

This report documents that warmer temperatures brought by climate change are making ozone more likely to form and harder to clean up. Significantly more people suffered unhealthy ozone pollution in the 2020 report than in the last three “State of the Air” reports.

Particle Pollution in Delaware

“State of the Air” 2020 found that the highest year-round particle pollution level in the Philadelphia metro area was slightly worse than in last year’s report, even though it still met the national standard for this pollutant. As a result, the metro area’s rank worsened from 18th worst in last year’s report to 12th worst in the United States in the 2020 report. 

In contrast, the only county in Delaware with enough data to be graded, Sussex, continued to improve, and earned a “Pass” grade. However, it should be noted that New Castle County, the county in the state historically with the highest averages for this pollutant has again been registered as having “Incomplete” data.  And in the Salisbury-Cambridge metro area, the worst level was posted outside of Delaware, in Dorchester County, MD.

“Particle pollution can lodge deep in the lungs and can even enter the bloodstream. It can trigger asthma attacks, heart attacks and strokes and cause lung cancer,” said Brown. Particle pollution comes from industry, coal-fired power plants, diesel emissions, wildfires and wood-burning devices.

“Year-round particle pollution levels had dropped in recent years thanks to the cleanup of coal-fired power plants and the retirement of old, dirty diesel engines. However, the increase we’ve seen nationally in particle pollution in this year’s report is a troubling reminder that we must increase our efforts to reduce this dangerous pollution,” said Brown.

“State of the Air” 2020 also tracked short-term spikes in particle pollution, which can be extremely dangerous and even lethal. On a positive note, the report found that Philadelphia-Reading-Camden, PA-NJ-DE-MD metro area again improved with fewer days when short-term particle pollution reached unhealthy levels. Delaware’s worst performance for this measure was recorded in the three days high in this pollutant experienced in New Castle County, for which it earned a “C.”

Even better, Kent and Sussex Counties earned “A” grades for fine particle pollution in this year’s report, posting zero days with average concentrations in the unhealthy ranges, according to the air quality standard. That placed these counties on the list of cleanest counties in the nation for this pollutant.

“We all have the right to breathe clean, healthy air. The 50th anniversary of the Clean Air Act serves as a critical reminder that Americans breathe healthier air today because of this landmark law,” said Brown. “At the same time, this year’s report shows that we must stand up for clean air—especially to safeguard our most vulnerable community members. Our leaders, both here in Delaware and at the federal level, must take immediate, significant action to ward off climate change and other threats to the quality of the air we all breathe.”

While the report examined data from 2016-2018, this 21st annual report also provides air pollution trends back to the first report. Learn more about the First State’s rankings, as well as air quality across the region and the nation, in the 2020 “State of the Air” report at For media interested in speaking with an expert about lung health, healthy air, and threats to air quality, contact Valerie Gleason at [email protected] or 717-971-1123.

For more information, contact:

Valerie Gleason
[email protected]

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