Traffic Emissions Account for 70% of External Matter Found in Urbanites’ Lungs: Study

Levels of pollution found in the lungs of Los Angeles residents rose and fell with the patterns of rush hour traffic, researchers found.

The findings of a new study warn that traffic emissions cause high levels of particulate matter and carbon to settle in the lungs of residents living in large, urban areas.

Researchers with the University of Southern California and Kuwait University examined lung-deposited surface area (LDSA) affected by particulate exposure in Los Angeles, finding that 70% of such deposits came from air pollution caused by traffic. According to the findings, published online in the journal Environmental Pollution on January 7, the amount of exposure appeared to rise and fall in patterns that matched rush hour in the mornings and evenings.

Particulate matter (PM 2.5) is a type of air pollution made up of ultra-tiny particles of soot, dirt and droplets, which are smaller than 2.5 micrometers, or 70 times smaller than the width of a single human hair. They may come from vehicle emissions, industry fumes or other sources of air pollution, and the microscopic particles can easily enter the airways and the bloodstream.

The researchers note that airborne particulate matter has been linked to respiratory problems including asthma and bronchitis, as well as an increased risk of heart attacks and strokes with long-term exposure.

In the new study, a research team led by Constantinos Sioutats, looked at the daily trends and sources of LDSA, the concentration of particles, as well as elemental carbon, and organic carbon concentrations in Los Angeles. They took hourly measurements across different seasons.

The researchers found there were peaks in the concentration of particles and LDSA in the early morning and evening, coinciding with periods of increased traffic volume during morning and evening commutes. During warmer seasons, they found an increase in the concentration of particles at midday due to photochemical reactions from heat. There were nighttime peaks during the colder months, due to aerosols forming more easily in wet conditions.

The formation of particles during warmer periods contributed to 19% of lung-deposited surface area particles in residents. Colder months and wet conditions accounted for 11% of lung-deposited surface area chemicals.

Researchers concluded that particulate matter in urban areas poses a serious risk to residents, calling for additional efforts to address traffic emissions in order to reduce the health risks.

Growing Concerns Over Particulate Matter

The findings come amid increasing evidence regarding a number of long-term health risks associated with exposure to air pollution. Due to risks faced in communities nationwide, last year the U.S. Environmental Protection Agency proposed a rule to reduce particulate matter in air pollution emissions, which would put a greater cap on the PM 2.5 that can be produced via manufacturing.

Another study last year, published by Harvard researchers, linked prenatal exposure to PM 2.5 to an increased risk of cerebral palsy. Other studies have linked particulate matter exposure to cardiovascular disease and impaired respiratory function. Even at low levels PM 2.5 can pose a risk to children’s long-term mental health and cognitive function.

In addition, particulate matter has been linked to an increased risk of breast cancer, particularly among Black and Latina women, who potentially face a greater risk due to environmental factors rather than genetic reasons.