The San Diego Coronado Bay Bridge bathed in the orange glow of a San Diego sunset. Photo Courtesy: Eileen Maher (Port of San Diego)

by Ryan Posner | SDSU student

One of San Diego’s most iconic structures may be exacerbating what is already a severe air quality problem in the neighborhood of Barrio Logan.

The San Diego Coronado Bay Bridge, located directly over a portion of Barrio Logan, is a gateway to the city of Coronado, and all its tourist attractions and military areas.

The neighborhood of Barrio Logan already deals with a high volume of harmful particulates because it’s so close to Interstate 5 and the Port of San Diego. Traffic on the bridge could be compounding this issue.

Burbank Elementary School is located in the census tract under the bridge, and just a few blocks from I-5.

“Those elementary schools need to have air filters so that children are not forced to breathe in these toxic emissions,”said Dr. Jenny Quintana of the Graduate School of Public Health at San Diego State. “When you’re dealing with black carbon, things like asthma and other lung disorders can occur.”

Barrio Logan has seen some decreases in emission causers. The Port of San Diego reduced its diesel emissions by 75 percent between 2006-2012, according to a U-T San Diego report.

San Diego City Councilman David Alvarez, whose district includes Barrio Logan, said the city is continuing to look at ways to further reduce emissions at the port.

Measures include requiring boats to enter the port at slower speeds, and using shoreline power at the docks, rather than allowing boats to idle and let off diesel emissions.

Not all methods of reducing emissions have to do with cars and ships, though.

“One thing we’ve been trying to do is plant more trees. We’ve been putting a lot of money into that,” Alvarez said.

The trees planted help reduce carbon dioxide emissions, says Alvarez.

Inversion Layers

Barrio Logan’s proximity to the ocean means moderate to low winds blow on average throughout the year.

But without strong winds, harmful particulate matter is not diluted.

“In areas of low wind and high pressure, particles can get trapped because of a warm temperature change,” said Kevin Robinson, a lecturer at  SDSU’s Department of Geological Sciences. “If it gets too windy, the particles can be diluted, but Barrio Logan does not have strong winds.”

The people who make their homes or have a business in this area are forced to cope with the poor air quality.

“It’s not obvious that this exact area has worse air quality than the rest of the neighborhood, but it’s alarming,” said Barrio Logan resident Jonathan Perez. “There’s routine traffic on the (I-5) and on the bridge, so these numbers make sense.”

Bridge traffic

According to a 2009 California Department of Transportation report, some 75,000 cars per day cross the bridge.

The traffic produces black carbon, which is regarded as the most harmful “fine” particle. “Fine” particles are defined as particulate matters that are 2.5 micrometers in diameter or less.

These particles are dangerous because they can be inhaled directly into the respiratory system, according to the federal Environmental Protection Agency.

“Black carbon is produced from diesel particulates, a lot of them are produced from big rig trucks and ships,” Quintana said. “Although, not as much black carbon is formed from the bridge traffic compared to the (I-5), because the amount of big trucks that use the (I-5).”

A study from the state Office of Environmental Health Hazard Assessment has shown that areas located under the bridge are suffering worse than most areas in Barrio Logan.

CalEnviroScreen measured particulate matter in the air measuring less than 2.5 micrometers (PM 2.5) and found Barrio Logan was in the 91-100th percentile for worst air quality in San Diego.

The area under the bridge scored within the 96-100th percentile for worst air quality.

With advances in technology, like the measuring tool CalEnviroScreen, people in Barrio Logan can access information on  air quality on a neighborhood level, rather than just a regional level.

“People have the power to know what’s in the air they’re breathing,” Quintana said.

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Ryan Posner was enrolled in San Diego State’s “What’s in the Air” sensor journalism class in Spring 2015.

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