Air pollution: Scientists focus on the small stuff

Jul. 14, 2013Houston Chronicle

A team of researchers at Rice University is gearing up to address a critical knowledge gap in the southeast Texas health picture – small-particle air pollution and who is being exposed to it.

If your knowledge of small-particle pollution is sadly out of date, it’s little wonder. For years, most air information in the Houston area has focused on lung-damaging ozone, or on air poisons such as benzene and butadiene.

But health researchers are increasingly concerned about particles and about how vague a picture they possess of concentrations in the eight-county area.

Hundreds of studies now implicate small particles in conditions that lower quality of life, from asthma to disabling stroke to, possibly, autism spectrum.

There is another imperative as well: The region is barely skirting a new, stricter federal limit on small particles.

The network of local air monitors that can measure fine particles is weak compared with the network for ozone. The gauges that do monitor small particles provide a level of data better suited to the last century. They can tell, for instance, the total mass of particles in a cubic meter of air that are smaller than the width of spider silk. But researchers nowadays want to know more; they want to know the makeup.

More sophisticated equipment “would show what percentage of the particles were sulfates, for example,” says Rob Griffin, a professor of civil and environmental engineering at Rice.

“That would indicate they probably came from coal-fired power plants. It would show what percentage are nitrates,” which would indicate they came from some kind of engine or burning. Black carbon, or soot, and ammonium are other major constituents of small-particle pollution and each helps sketch in the picture of these pollutants’ origin.

In September, the Rice researchers together with Barry Lefer, an atmospheric scientist at the University of Houston, will pilot a mobile laboratory capable of making such distinctions, in nearly real-time. They’ll gather samples all day. Then they will use that data to design a year-long mobile monitoring campaign.

But even before that, in the next couple of months, two other Rice researchers in collaboration with the University of Texas Health Science Center at Houston School of Biomedical Informatics will take air data from the monitors that do already exist plus patient medical records, and they will combine these two sets of information in novel ways.

Rachel Kimbro and Justin Denney, director and associate director of the Kinder Institute Urban Health Program at Rice, both sociologists, have gained access to hundreds of thousands of emergency room, outpatient and clinic records from the University of Texas. An informatics team there has been putting that data into analyzable form. Kimbro and Denney will spend the summer matching this treasure trove of patient data with air information from the existing network small-particle monitors.

Particle hot spots?

“Then we can start to analyze a host of cardiovascular health events that people have experienced over the years,” says Denney.

Kimbro says they hope to determine whether the risk from fine particles is spread equally around the urban area or whether there are particle hot spots.

“We are hoping to compare neighborhoods in Houston – which have similar compositions by race, ethnicity, income and education – one of which is closer to a hot spot and one of which is further from a hot spot,” Kimbro says. “This will let us more clearly test whether health differences across neighborhoods may be due to different exposures.”

One thing they will not be able to identify this summer is whether particle pollution is contributing to health issues on the west side. That’s because there are no monitors checking for small particles on the west side.

“Unlike other health hazards, air is everywhere, Denney said. “We’re all exposed to it.”

The two complementary projects, which are funded by the Houston Endowment, will provide a check for each other in pinpointing vicinities of high small-particulate pollution.

The issue of particle pollution is one that has risen high on the horizon for communities across the country in recent years, especially port communities such as Los Angeles, Long Beach, Calif., Seattle and Newark, N.J. As ports have tried to expand, often to accommodate giant Panamax vessels through a widened Panama Canal, these communities have cried foul, demanding pollution reductions in exchange.

Port areas affected

Over the last decade, the ports of Los Angeles and Long Beach have been forced to pressure their clients – international shipping companies such as COSCO – to switch to cleaner diesel fuel as they edge into port. They also pressured trucking companies that call on the ports to retire older trucks. Newer ones burn dramatically cleaner. And they’ve switched to electric port equipment, all with the result that particle emissions have plummeted.

Port neighborhoods in Houston may be starting to organize as well. Two hundred people attended a town meeting at Holland Middle School in May. Patricia Gonzales, a mother of three from Pasadena and member of the Texas Organizing Project, was one.

“We want to know what’s going on around us and how it will affect our everyday lives,” she said. Speakers asked for a seat on the Port of Houston Authority Commission.

Residents in Utah also have recently become energized. Utah is trying to reduce particulate levels by 40 percent. There, the main particle sources are thought to be metal smelters, manufacturing, auto body shops and, of course, cars.

Both California and Utah plan to require reductions in emissions from certain types of commercial char-broilers that use conveyor chains to move hamburger patties through a flame.

Another impetus for the changes is long-anticipated restrictions on particles from the Environmental Protection Agency. Last December, the agency lowered allowable annual averages of the small particles to 12 micrograms per cubic meter.

The Houston area is thought to be on the verge of conforming to the new limits.

About 44 million Americans live in counties that would not comply if the new limits came into force today. But EPA projects that by 2020, when all regions of the country must comply, only seven California counties will not. Bakersfield, Calif., currently has the country’s highest levels. That region’s plan includes limits on flaring, open burning, prescribed forest burns, confined animal facilities, and asphalt and concrete operations.

Exposure to fine particles, even over short periods, can cause premature death, heart attacks and asthma attacks.

More recent findings

Just a few weeks ago, researchers at the University of Michigan School of Public Health found faster hardening of the arteries for people who live in dirtier neighborhoods compared with cleaner ones in the same cities. They used ultrasound to measure thickening of the carotid artery. When pieces of plaque or blood clots from arterial walls break off and flow to the brain, they can cut off blood flow, causing stroke or death.

Recent findings published by the European Association for the Study of Diabetes show an increase in insulin resistance with exposure to more small air particles. When the body is resistant to the sugar-counteracting hormone insulin, blood-sugar levels can soar.

On the hopeful side, other new research from the Harvard School of Public Health indicates even small improvements in particle pollution may lead to longer life.