Unequal Pollution

Most of Orange County, CA has very little tree canopy. Areas in dark green have more tree coverage. Generally, disinvested communities have fewer trees.

A tree’s canopy cover - its leaves, branches, and stems that provide the tree coverage of the ground when viewed from above - is a driving force behind numerous environmental, social, and economic services. Reducing summer peak temperatures, improving air quality, reducing stormwater run-off, and enhancing property values are just a few of the services dense tree cover can provide to a community.

Impervious surfaces, shown in blue such as concrete, tend to retain heat and increase runoff during rain events, which contributes to the formation of urban heat islands (UHIs). As a result, temperatures in these urban areas are often higher than those in surrounding non-urban regions.

Air pollution is primarily assessed through two measures: Particulate Matter (PM) concentration and ozone levels. Both of these factors are associated with short-term and long-term adverse health effects, including an increased risk of cancer.

Neighborhoods with high concentrations of low-income families and people of color are more likely to be exposed to environmental hazards putting them at higher risk for chronic diseases and premature death. Levels of pollution exposure are higher in Orange County for nearly all broad racial/ethnic groups than in California or the United States overall.

Historically, air pollution in Orange County derives from the exhausts of motor vehicles, particularly diesel trucks. In 2021, motor vehicles emitted 15.2 tons of organic gasses per day, according to the California Air Resources Board. 

Indicator: Mixture of particles in diesel exhaust in the air, measured as micrograms per cubic meter.

Transportation and wildfires are two of the main contributing factors of air pollution in Southern California.

Indicator: Number of vehicles (average annual daily traffic) at major roads within 500 meters, divided by distance in meters.

Exceedance of state ozone standards is another key indicator of air pollution. Elevated temperatures contribute to increased ground-level ozone and other pollutants, which can react chemically with emissions from power plants and vehicles. This, in turn, leads to diminished air quality.

 _{Data Source: Justice40} 

Recent research has shed light on the significant health burdens caused by environmental factors. Among the most prominent health outcomes associated with these factors are asthma, cardiovascular disease, low birth weight, and cancer.

Each health indicator is divided into quintiles, with red representing areas experiencing the greatest burden and blue indicating a lesser burden. As the color shifts from pink to blue, the burden decreases. In the conditions we're examining, disinvested communities predominantly reside in areas with higher risks for negative health outcomes

Research shows that air pollution can worsen asthma symptoms. A study of young campers with moderate to severe asthma showed they were 40 percent more likely to have acute asthma episodes on high pollution summer days than on days with average pollution levels.

Indicator: Asthma attacks that resulted in an emergency department visits per 10,000 people.

A large body of science has shown that air pollution can exacerbate existing cardiovascular disease and contribute to the development of the disease. The evidence is particularly strong for outdoor particle pollution exposure.

Indicator: Heart attacks per 1,000.

Pregnant women and fetuses are sensitive to air pollution due to physiological changes in pregnancy. Early exposure in pregnancy can lead to pre-term labor and subsequently low weights at birth for infants.

Indicator: % of infants born weighing <5.5lbs.

Air pollution is a leading cause of insulin resistance and incidence of type 2 diabetes. The association between air pollution and diabetes is stronger for traffic associated pollutants, gaseous, nitrogen dioxide, tobacco smoke, and particulate matter.

Indicator: Share of people ages 18 years and older who have been told by a health professional that they have diabetes during pregnancy.