• Written by Jonathan Colmer, Assistant Professor of Economics, University of Virginia

Air pollution contributes to as many as 9 million premature deaths worldwide each year – twice as many as war, other violence, HIV/AIDS, tuberculosis and malaria combined[1]. Fine particulate matter air pollution is especially dangerous: Microscopic particles readily enter the lungs, bloodstream and brain, with health effects[2] that include infant death, reduced life expectancy for adults, cancer, lung disease and heart disease.

Fine-particle air pollution has decreased across the US, but poor and minority communities are still the most polluted Fine particulate air pollution is referred to as PM2.5 because the particles are less than 2.5 microns in diameter – 40 times smaller than a grain of sand. Washington department of Ecology[3]

Fine particle matter pollution concentrations in the United States have declined by roughly 70% since 1981. However, in a newly published study[4], we show that the areas that were most polluted in 1981 are still the most polluted today, and the least polluted areas in 1981 are still the least polluted today.

Areas that were whiter and richer in 1981 have become relatively less polluted over time. Areas that became whiter and richer between 1981 and 2016 have become relatively less polluted over time. In contrast, the neighborhoods and population groups that were most exposed to fine particle pollution 40 years ago – disproportionately low-income and minority communities – are still exposed to higher pollution levels.

As scholars who focus on environmental economics[5] and public policy[6], we believe that the persistence of air pollution disparities matters. We care about who is advantaged and disadvantaged. In addition, our results have implications for environmental public policy. To the extent that policy aims to reduce pollution disparities, the job is far from finished.

Mapping pollution at a neighborhood scale

Researchers have known for decades that air pollution varies across locations due to economic activity, climate and other factors. It is also well documented[7] that lower-income households, people of color and other disadvantaged communities are disproportionately exposed to air pollution. Since research shows that air pollution is associated with early death, lower educational attainment and lower lifetime earnings[8], these differences promote economic, health and social inequality[9].

What has not been clear is how much air pollution disparities have changed over time. We wanted to understand particulate matter air pollution disparities in a more systematic way, for the entire U.S. over many years.

Until recently, the information needed to answer this question simply wasn’t available. The U.S. Environmental Protection Agency monitors levels of fine particle pollution[10], known as PM2.5, nationwide. But its monitors offer relatively sparse coverage and are concentrated in disproportionately urban locations.

In our study, we leverage newly available data[11] that captures PM2.5 concentrations at more than 8.6 million distinct U.S. locations from 1981 through 2016. These data were constructed from satellite observations and pollution transport modeling, along with pollution monitor records. They provide a detailed year-by-year picture of fine particulate matter concentrations for each of the roughly 65,000 Census tract “neighborhoods” in the United States.

Fine particle air pollution moves from the lungs into the bloodstream and can have widespread health impacts throughout the body.

Persistent disparities

Our analysis shows that there has been some progress over the past 35 years in reducing gaps between the most polluted and least polluted locations. In 1981 PM2.5 concentrations in the most polluted 10% of census tracts averaged 34 micrograms per cubic meter. PM2.5 concentrations in the least polluted 10% of census tracts averaged 13 micrograms per cubic meter. The difference was 22 micrograms per cubic meter.

In 2016 PM2.5 concentrations in the most polluted 10% of census tracts averaged 10 micrograms per cubic meter. PM2.5 concentrations in the least polluted 10% of census tracts averaged 4 micrograms per cubic meter. The difference was 6 micrograms per cubic meter.

These reduced gaps likely imply that differences in pollution-induced health, wealth and productivity across locations are also declining. But while pollution gaps have declined for some disadvantaged communities, this hasn’t been universal.

Next we wanted to see whether specific locations had more or less pollution than other locations, and whether the most polluted locations were the same through time. To explore these questions, we ranked each neighborhood from most polluted to least polluted for every year that we had data.

We then evaluated how these rankings changed between 1981 and 2016, and found that they remained remarkably persistent. The most polluted areas in 1981 remain the most polluted areas today, and the least polluted areas in 1981 remain the least polluted areas today. Communities that were disadvantaged in 1981 remain exposed to higher levels of pollution today. If anything, relative disparities have worsened for poorer and Hispanic communities.

While PM2.5 concentrations decreased nationwide between 1981 and 2016, the same areas generally are still most and least polluted.

A disproportionate share of the most polluted areas over the past 40 years are in Southern California, while the least polluted areas are more dispersed across the U.S. As an example, a child born in Los Angeles County in 2016 was exposed to 42% more fine particle pollution than the average child born in the United States, and 26% more pollution than a child born in New York City.

A few areas did see improvements or declines in their relative standing. Ohio, West Virginia, eastern Kentucky and the Northeast Corridor became relatively less polluted from 1981 through 2016. California’s Central and Imperial valleys, southwestern Arizona, southern Texas and portions of Arkansas and Oklahoma became relatively more polluted.

Fairness, equity and public policy

Our findings underline the scope, scale and persistence of air pollution disparities in the United States. But if particulate matter air quality has improved over time – which should translate into improvements in health, wealth and productivity for most Americans – why should we be concerned about relative disparities between some locations and others?

[Deep knowledge, daily. Sign up for The Conversation’s newsletter[12].]

In our view, persistent disparities between the most and least polluted communities matter because fairness, equity and justice are relative concepts. We define them based on who is advantaged and who is disadvantaged at any given time. Pollution disparities translate into health, economic and social disparities.

For decades, federal and state environmental guidelines have aimed to provide all Americans with the same degree of protection from environmental hazards. The EPA’s definition of environmental justice states that “no group of people should bear a disproportionate share of the negative environmental consequences[13].” On this front, our research suggests that the United States is falling short.

Ian Hardman, research associate at Stanford University’s Program on Energy and Sustainable Development, and John Voorheis, lead economist at the U.S. Census Bureau’s Center for Economist Studies, co-authored the study described in this article. Any opinions and conclusions expressed here are those of the authors and do not necessarily reflect the views of the U.S. Census Bureau.

Authors: Jonathan Colmer, Assistant Professor of Economics, University of Virginia

Read more

Metropolitan republishes selected articles from The Conversation USA with permission

Visit The Conversation to see more

Entertainment News

A retrospective on Frasier, America’s sitcom set in Seattle

2020 marks the 27th anniversary of America’s popular TV show Frasier. The well-loved sitcom, which can be viewed in Australia on 10 Peach and streamed on Stan and Foxtel, had an 11-year run and ...

Polly Simmons - avatar Polly Simmons

BRANDYN CROSS: “If Money Talks (It Ain’t Sayin’ Much to Me)”

“If Money Talks (It Ain’t Sayin’ Much to Me)” Embracing an empowering “carpe diem” aesthetic ever since a tragic accident changed the trajectory of his life, the multi-talented- and autistic- ...

News Company - avatar News Company

Violin ReEnvisioned

Falling in love with music so young was more than transformative. Music became the lead sheet of my life; challenging me to navigate changes with grace, maintain a steady rhythmic groove, dynami...

Chelsey Green - avatar Chelsey Green

Kadda Sheekoff Win Best Urban Song For "All My Life"

Singer Kadda Sheekoff have emerged as the toast of the 2020 Songdew Pause&Play. Obviously, there are many composers who deserve the award more than Kadda Sheekoff, but the decision of the S...

Media Release - avatar Media Release

A Musical Journey: The Authentic Ted Cline

Ted Cline was born in 1962 as the 11th of 13 children.  His parents were hard-working tobacco share-croppers in Weston, Missouri. By the time he was eleven, he was sneaking downstairs to play his...

Ted Cline - avatar Ted Cline

Angela Predhomme - My Musical Journey

Determined to “make it” in the music industry as a songwriter, I meticulously crafted the best songs I could and pitched them to industry gatekeepers. “THIS one’s got to be IT,” I thought. But ala...

Angela Predhomme - avatar Angela Predhomme

GREYE: “So Far So Good”

“So Far So Good” After seven plus years firing up venues up and down the Atlantic Coast and throughout the Midwest to the breakneck tune of 90-110 annual shows, it’s definitely been jarring fo...

News Company - avatar News Company

The life and times of Wendy Moten

I never thought I would be in the music business, much less a recording artist. I never saw it coming. I thought I'd be a corporate attorney or something like that. Little did I know that anothe...

Wendy Moten - avatar Wendy Moten

CARY PARK “You Matter to Me”

“You Matter to Me” In any other time, Cary Park’s stunning new single “You Matter to Me” might be just another beautiful heartfelt love song, an outpouring of personal affection towards a cheri...

News Company - avatar News Company

Metropolitan Business News


In 2019, just as his multi-faceted career was taking off, Thorn Castillo heard Robert Downey Jr. offer a sage bit of advice during an interview on photographer/director Sam Jones’ acclaimed multi-...

News Company - avatar News Company

New Research Highlights Opportunities for Sports Betting

Revenue Stream for Sports’ Post-COVID-19 Recovery Strategies New Rochelle, NY, June 1, 2020— Twenty-four states have now legalized sports betting, with more states considering legalization la...

Len Stein - avatar Len Stein

How to make overseas transfers easier?

Mainstream banks can charge as much as $20 just to process a basic international money transfer. Fortunately, today people are not doomed to handling personal finances only through mainstream gl...

News Company - avatar News Company

The flourishing international market of fragrance and perfume

There is something special and unique about the art of fragrance. This is a big world and there are quite literally a lot of smells around at any given time. In fact, as one of the five human senses i...

News Company - avatar News Company

Impact of good marketing on sales

Sales and marketing are brothers as they go hand and in hand. The job of both of these departments is to generate revenue so that an organization can make money. A company that does not generate rev...

News Company - avatar News Company

7 effective tips for increasing sales in retail

It seems that retailers have drawn a difficult lot in the 21st century: competition from online retail is growing steadily. After all, Internet retailers can sell your products at significantly lowe...

News Company - avatar News Company



Are you planning to go on a trip? Possibly, you do not know what things are most necessary on a trip. In this article, we will guide you through some important tips. These tips help you to...

News Company - avatar News Company

New Baggage Regulations to Help Aussie Parents Travel with Infants

Travelling around the globe has never been easy, especially when infants tag along for the trip. One of the main issues that parents often have to deal with is the need to bring extra item...

News Company - avatar News Company

Maya Beach Opens to Tourists

Despite recent reports that Southern Thailand's famous Maya Beach will close for three months this year, in fact no decision to this effect has been made by Thai authorities. Phi Phi Nati...

Maevadi Rosenfeldt - avatar Maevadi Rosenfeldt