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Smog forms in the atmosphere when emissions of nitrogen oxides and volatile organic compounds “cook” in the sun from sources like automobiles, industries, power plants and chemical fumes. Those most at risk include people with asthma, children and older adults, as well as those who are active or work outside.
The agency is looking to increase the standards within a range of 65 to 70 parts per billion (ppb) to better protect Americans’ health and the environment, while taking comments on a level as low as 60 ppb. The last update came in 2008, setting them at 75 ppb. The existing Clean Air Act requires EPA to review the standards every 5 years by following a set of steps and considering the advice of an expert panel.
EPA scientists examined numerous studies in its most recent review, including more than 1,000 new studies published since the last update. Those indicate that exposure below 75 ppb, which is the current level, can pose serious threats to public health, cause respiratory distress and illness, and is linked to premature death from both respiratory and cardiovascular causes.
The new standards will also provide an added measure of protection for low income and minority families who are more likely to suffer from asthma or to live in communities that are overburdened by pollution. EPA thinks that strengthening the standard will especially help children - preventing both asthma attacks and keep them from missing school. They estimate that the benefits of meeting the proposed standards will significantly outweigh the costs. If the standards are finalized, every dollar invested in them will return up to three dollars in health benefits.
The Clean Air Act says that depending on the severity of the problem, areas would have between 2020 and 2037 to meet the standards. To ensure that people are alerted when ozone reaches unhealthy levels, EPA is proposing to extend the ozone monitoring season for 33 states. This is particularly important for at-risk groups, so they can take steps to protect their health on smoggy days.
The agency is also proposing to strengthen the “secondary” smog standard to a level within 65 to 70 ppb to protect plants, trees and ecosystems. New studies add to the evidence showing that repeated exposure stunts the growth of trees, damages plants and reduces crop yield.
EPA will seek public comment on the proposal for 90 days following publication in the Federal Register, and plans to hold three public hearings. They will issue final ozone standards by Oct. 1, 2015.