by Ryan Posner | SDSU student
Most people assume wind would affect air quality, which is true, but what they may not realize is that a lack of wind can have a harmful impact on air quality in certain areas.
One of those areas is Barrio Logan.
Not only is it located next to Interstate 5, but it’s also next to the Port of San Diego and San Diego Airport. These are areas of heavy traffic for cars, ships, planes and industry, which let off harmful emissions.
Being situated next to San Diego Bay, Barrio Logan gets a constant sea breeze, which starts about midday and lasts through the day, according to Kevin Robinson, a lecturer at SDSU’s Department of Geological Sciences.
These sea breezes are created by uneven pressures from a body of water and land.
Wind can carry “fine” particles — particles less than PM 2.5 in diameter — during rush hour traffic on I-5, during plane and port activity.
Robinson says it’s the lack of wind strength, though, that could be hazardous for the neighborhood.
“Unless there is a storm, there’s going to be moderate to light wind in an area that’s close to the ocean,” Robinson said. “Light wind can be worse than moderate to strong wind, because stronger winds can dilute the particles by spreading them out. If the wind is light, though, then the particles just sit there.”
According to the Beaufort Scale, which is an empirical measure that matches wind speeds with observed conditions, moderate winds are between 12.2-17.9 MPH.
Anything below that number is considered a light wind.
San Diego airport wind readings, according to the National Weather Service, indicate that the average wind speeds at the airport from 2007-2015 have fallen between 7-9 MPH.
On the Beaufort Scale, that is classified as a light breeze to a gentle breeze.
Because the sea breeze is not strong in Barrio Logan on average, particles, which include toxic emissions, can stay around longer.
According to a report from the California Environmental Protection Agency in 2014, Barrio Logan was listed as the 99th most hazardous neighborhood out of 8,035 census tracts in the state.
“If you decide to live in this neighborhood, those are numbers you are just going to have to deal with,” said Barrio Logan resident Lance Johnson. “There are ways to help ease the problem but it’s still going to be there.”
Dangers of black carbon
The most dangerous of these emissions is black carbon, which is the strongest light-absorbing component of particulate matter. It’s created through a combination of fossil fuels, biofuels and biomass.
Dr. Jenny Quintana of the SDSU Graduate School of Public Health said, “When you look at PM 2.5 that’s just talking about the particle size, what really makes it dangerous is when there are black carbon particulates.”
Black carbon is listed as a known carcinogen by the International Agency for Research on Cancer and has been known to cause conditions such as asthma.
“Black carbon being created by major highways and other activities without a lot of wind strength to dilute it is a major hazard,” Robinson said. “These can create inversion layers which are very harmful.”
An inversion layer is an increase in temperature with height, or to any layer in which the increase occurs.
These layers can lead to smog being trapped close to the ground and are common in areas of oceanic upwelling such as Barrio Logan.
“Without moderate or strong winds the pollution that is created in this neighborhood is possibly just sitting there in one of these layers,” Robinson said.
Addressing the problem
What can San Diego do to limit these emissions?
In December 2007, the state’s Air Resource Board mandated the “Airborne Toxic Control Measure for Auxiliary Diesel Engines Operated on Ocean-Going Vessels At-Berth in a California Port.”
The mandate gave California’s ports two options to reduce emissions, “1) turn off auxiliary engines and connect the vessel to some other source of power, most likely grid-based shore power; or 2) use alternative control techniques) that achieve equivalent emission reductions.”
“We’ve been doing a lot to address the issue of air quality in the Barrio Logan neighborhood by cutting down on our emissions tremendously,” said Michelle White, the port’s environmental policy manager . “We’ve also reduced our greenhouse gases and want to do our best in our local and global community.”
“Some of the ways we’ve been able to do this have been using cleaner fuels, having ships enter at slower speeds and having ships hook up to electrical docks, instead of just idling and letting off diesel emissions.”
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Ryan Posner was enrolled in San Diego State’s “What’s in the Air” sensor journalism class in Spring 2015.