Today, let’s take a look at the proposed changes to National Ambient Air Quality Standards for ozone.  For more information on ozone, take a look at some past blog posts that focus on this molecule, its generation, dangers and uses.

National Ambient Air Quality Standards are required limits set by the EPA, as required by the Clean Air Act.  These limits are established for pollutants that are harmful to public health and/or the environment.  The Clean Air Act was last updated in 1990.  At that time, there were two standards set, the primary and the secondary standards.  Primary standards are those that are set in order to protect the health of the general public, with special consideration to those with breathing issues, the young and the elderly.  Secondary standards are more general and include protection against damage to the environment, crops, animals and structures.  The current standards are:

NAAQS resized 600Source:

In January 2010, the EPA released a proposal to change the primary and secondary standard for ozone levels, which were last revised in March 2008 (to read the full proposal, click here).

The proposal seeks to decrease the ozone primary standard from 0.075 ppm to between 0.060 to 0.070 ppm.  The decrease was proposed “to provide increased protection for children and other ‘‘at risk’’ populations against an array of O3-related adverse health effects that range from decreased lung function and increased respiratory symptoms to serious indicators of respiratory morbidity including emergency department visits and hospital admissions for respiratory causes, and possibly cardiovascular-related morbidity as well as total non-accidental and cardiopulmonary mortality.”

The proposal goes further to recommend the secondary ozone standard be changed to reflect the seasonality of ozone levels.  According to the proposal, instead of a fixed number, the new standard, “should instead be a new cumulative, seasonal standard expressed as an annual index of the sum of weighted hourly concentrations, cumulated over 12 hours per day (8 am to 8 pm) during the consecutive 3-month period within the O3 season with the maximum index value, set at a level within the range of 7 to 15 ppm-hours.”  This change would serve to protect the environment from the impacts of high ozone levels.

When an area fails to meet this standard, it is referred to as a “nonattainment” area.  The below map shows the areas that failed to meet the standard as of the last report, April 2011.

NAQQS ozone map


As with any proposed change, there are those that will oppose it.  Just this week, the National Association of Manufacturers sent a letter to President Obama and EPA Administrator Jackson asking that they reconsider the effects of this change in legislation.  The letter, signed by 35 different state manufacturing associations, states that changing the standards will cause “unnecessary and severe economic harm,” “will almost triple the number of counties designated as being in violation of the Clean Air Act,” and will therefore discourage “new businesses from locating in non-attainment areas and restricting the growth of existing businesses.”  To read the full letter, click here.

The most recent notice on the status of the proposal was released on July 26, 2011.  The statement read:

Administrator Jackson is fully committed to finalizing EPA’s reconsideration of the Clean Air Act health standard for ground level ozone. That reconsideration is currently going through interagency review led by OMB. Following completion of this final step, EPA will finalize its reconsideration, but will not issue the final rule on July 29th, the date the agency had intended. We look forward to finalizing this standard shortly. A new ozone standard will be based on the best science and meet the obligation established under the Clean Air Act to protect the health of the American people. In implementing this new standard, EPA will use the long-standing flexibility in the Clean Air Act to consider costs, jobs and the economy. (source:

Follow us so we can keep you up to date of all changes!  To learn about the Environics systems that facilitate dynamic calibration of ambient air analyzers, click here.