On February 2, 2015, at the invitation of the Environmental Protection Agency (EPA) seeking comments on the optimal level of ozone for public health, Kent Pinkerton, PhD, Core Scientist in the CNPRC Respiratory Diseases Unit and for the Inhalation Exposure Core, presented the scientific basis for requesting that national ozone standard be set at 60 ppb. He and co-researchers estimate that, at this level of ozone, between 5,210 and 7,990 premature deaths would be prevented annually. Dr. Pinkerton conducts studies on the health effects of inhaled environmental air pollutants, and is the Director of the Center for Health and the Environment at UC Davis.

Ozone, a key component of smog, forms in the atmosphere when emissions of nitrogen oxides and volatile organic compounds “cook” in the sun. Emissions from sources such as cars, trucks, buses, industries, power plants, and products such as solvents and paints are among the major man-made sources of ozone-forming emissions.

People most at risk from breathing air containing ozone include: children; people with asthma and other respiratory diseases; older adults; and people who are active outdoors, especially outdoor workers. An estimated 25.9 million people have asthma in the U.S., including almost 7.1 million children. Asthma disproportionately affects children, families with lower incomes, and minorities, including Puerto Ricans, Native Americans/Alaska Natives and African-Americans.

At the EPA public hearing in Sacramento, Dr. Pinkerton and other members from Physicians for Social Responsibility (PSR) testified on proposed updates to the national air quality standards for ground-level ozone. Based on an extensive body of scientific evidence, the EPA is proposing to update both the primary ozone standard, to protect public health, and the secondary standard, to protect the public welfare. The EPA has proposed to strengthen the ozone standard to a level between 65 to 70 ppb, which will improve public health protection, particularly for children, the elderly, and people of all ages who have lung diseases such as asthma. In California alone, this level of ozone is anticipated to annually prevent:

  • 110 to 430 premature deaths;
  • 67 to 130 cases of acute bronchitis in children;
  • 340 to 740 asthma-related emergency room visits;
  • 99,000 to 210,000 asthma attacks in children;
  • 110,000 to 230,000 days when children school; and
  • 5,500 to 11,000 days when people miss work.

“The California Central Valley has the dubious distinction as serving as the home to five of the top seven cities suffering with the greatest ozone levels in the country. Now is the time for the U.S. Environmental Protection Agency to do their job to enforce an ozone standard of 60 ppb to more fully protect all ages (human and animal) in the California Central Valley and the nation. We will all breathe easier.” emphasizes Dr. Pinkerton. 

The EPA estimates that meeting the new standards will also yield significant nationwide health benefits valued at $1.1 to $2 billion annually after 2025 for a standard of 70 ppb, and $2.2 to $4.1 billion for a standard of 65 ppb. These benefits include the value of avoiding asthma attacks, heart attacks, missed school days and premature deaths, among other health effects.

The Clean Air Act requires the EPA to review these standards every five years. The EPA last updated the standards in 2008. Protecting air quality is a federal/state partnership, and the EPA, states and tribes have made significant progress reducing ozone. Nationwide, ozone levels have dropped by a third since 1980 at monitor sites that track ozone trends. Ozone levels declined 18 percent from 2000 to 2013.

A significantly expanded body of scientific evidence, including more than 1,000 new studies since the last review of the standards, shows that ozone can cause a number of harmful effects on health and the environment. Exposure to ozone can cause respiratory system effects such as difficulty breathing and airway inflammation. For people with lung diseases such as asthma and COPD (chronic obstructive pulmonary disease), these effects can lead to emergency room visits and hospital admissions. Studies have also found that ozone exposure is likely to cause premature death from lung or heart diseases. In addition, evidence indicates that long-term exposure to ozone is likely to result in harmful respiratory effects, including respiratory symptoms and the development of asthma.

Although the EPA’s staff concluded that scientific evidence supports a standard within a range of 60 to 70 ppb, they did not include a standard of 60 ppb in the proposed range because of uncertainty in their scientific evidence at lower ozone concentrations. This uncertainty reduced confidence that ozone standard levels below 65 ppb would result in additional health improvements, compared to improvements that would result from a standard in the proposed range of 65 to 70 ppb.

While the current EPA proposal of 65 to 70 ppb is an improvement from the current standard of 75 ppb, Dr. Pinkerton and the PSR are asking the EPA to set the standard at 60 ppb, based upon the results of extensive scientific studies at UC Davis and the CNPRC.

Dr. Pinkerton’s research on the effects of ozone has been a concerted, multi-investigator approach using animal studies to understand the basic mechanisms underlying lung injury, coupled with epidemiological studies to assess the impact of ozone on human disease. These studies are combined with an extensive review of the current literature to aid in predicting adverse health outcomes based on ozone levels.

Based upon the current monitoring of ozone levels throughout the United States, these scientists are confident that the lowering of the ozone standard to 60 ppb will clearly benefit the well-being of many, but especially children, the elderly and those with pre-existing cardiorespiratory disease.

Additionally, ongoing research worldwide shows that temperature and other meteorological changes associated with the changing climate have the potential to offset some of the future improvements in allowable levels of ozone.

The Central Valley of California has already noted the impact of climate change on ozone levels. The potential effects of climate change have been seen in poorer respiratory health due to heightened ozone levels, increased airborne particulate matter due to dusts and wildfires, as well as a more intense and longer season of airborne pollens and spores, underscoring the need to address both ozone levels and climate change.