Caesar Rodney Insitute

Contrary to oft-stated comments, Delaware meets all federal air quality standards. The US Environmental Protection Agency (EPA) sets the National Ambient Air Quality Standards (NAAQS). Those standards are reviewed regularly.

EPA Administrators make the final decisions and routinely state, "The NAAQS identify what is considered a safe level of each pollutant to breathe, based on the most recent health and medical science, including an adequate margin of safety for those most at risk." This has been true in the Obama, Trump, and Biden Administrations.

The most recent review of the Nitrogen Dioxide (NO₂₎ standard was completed on January 16, 2025, so all recent relevant research papers have been considered. There are seven pollutants with standards, but only three are of current concern and emission data is given in Table 1 below.

The only reason the particle (PM_2.5) results were so high was because we had an extended period of wildfire smoke from Canada in 2023. The 2024 annual average was only 6.91. The EPA has a process for declaring high readings as “Exceptional Events” that can be excluded, but the process to apply is lengthy and expensive, so application is reserved for occasions when these exceptional events lead to failure to meet the standards.

Why Are Emission Trends Important?

The EPA publishes emission trend data highlighting Delaware easily meets the EPA air quality standards for NO₂. See below:

Since the peak in 1980, NO₂ emissions fell 85% from highway vehicles and 89% from electric generation by 2023.
In its 2018 review of the NO₂ NAAQS, the EPA stated, “The EPA anticipates that NO_X emissions will continue to decrease over the next 20 years” and “currently there are no areas in the United States that are designated as non-attainment for the NO_2.”
Standards for light-duty vehicle emissions continue to tighten through 2025, and emissions fall as older vehicles exit the market
Our regional electric grid manager, PJM, reports NO_X fell 90% from 2005 to 2024, and SO₂ fell 96%, and this is a primary precursor for PM_2.5.

NOTE: There is only one Air Quality Monitor (AQM) that is still monitoring NO_2,which is located 900 feet east (downwind) of I-95 on Martin Luther King Blvd. in the heart of Delaware’s most urban location. In 2024, the highest day registered was 45.4 PPB. The three-year annual average from 2022 to 2024 was 19 PPB. The most critical comment on the NAAQS review below was the daily standard should be dropped from 100 PPB, 98^th percentile to 50 PPB, 99^th percentile, and the annual standard should be dropped to 30 PPB. So, even those standards would have been met. In the 2018 NAAQS review of the primary standards, the Administrator decided to keep the current standards and a just completed EPA review did the same.

The American Lung Association Report: Misleading Claims

The American Lung Association (ALA) states in its 2024 Air Quality Report, “The NAAQS identify what is considered a safe level of each pollutant to breathe, based on the most recent health and medical science, including an adequate margin of safety for those most at risk.”

However, the ALA ignores the EPA’s NAAQS and goes on to create its own pollution standards by:

Using the 4^th highest day for ozone and the 98 percentile, or the 7^th highest day for PM_2.5.
Focusing on the highest day emissions excluded explicitly by the EPA.
Ignoring the issues of high days caused by wildfire smoke that are out of the control of individual states.
Ignoring NO₂, which has reached such a low level of emissions that only one air quality monitoring station in Delaware continues to measure it.

As a result of the above, in the 2024 ALA report, Delaware “grades” were based on 2020-2022 data lists two high ozone days in Kent County, four high days in New Castle County for ozone, and two high PM_2.5 days in New Castle County. This resulted in a “B” grade for Kent County, and a “C” grade for New Castle County.

Those high readings occurred on just three calendar days in 2021, and all those days had wildfire smoke-related warnings from fires on the West Coast. That smoke reportedly caused health concerns all the way to Europe.

High wildfire smoke days should be excluded from the ALA score. The three-year period covered in the report totaled 1,096 days. That means Kent County had a 99.8% positive score and New Castle County had a 99.7% positive score. Both counties should receive an “A.”

NOTE: While claims about long-term NO₂ pollution exposure leading to childhood asthma still exist, the EPA reviews do not support those claims. The 2018 NAAQS review stated, “Key epidemiologic studies conducted in the U.S. or Canada consistently report associations between long-term NO₂ exposures and asthma development in children in locations likely to have violated the current standards over at least parts of study periods, but that those studies do not indicate such associations in locations that would have clearly met the current annual and 1-hour standards.”

The Real Threat: Energy Reliability

If we are concerned about health impacts, we need to avoid electric power blackouts which have major negative health impacts, and can actually kill people. We need to make sure we have reliable power and putting too much emphasis on unreliable wind and solar power and a carbon tax that doesn’t work will not do that.

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For Further Research, below are previous Caesar Rodney Institute research articles on Air Quality in Delaware:

Energy Updates

Delaware continues to meet federal air quality standards

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