Statement of Deborah Shprentz

Consultant to the American Lung Association

EPA Public Hearing

On EPA’s Proposal to Retain the Existing 

National Ambient Air Quality Standards (NAAQS) for Carbon Monoxide (CO)

and to Revise the Minimum Monitoring Requirements

February 28, 2011

Arlington, Virginia

Good Morning. My name is Deborah Shprentz and I am a consultant to the American 

Lung Association. 

I wish to offer some preliminary comments and observations on EPA’s proposal. 

In brief, we believe that EPA must strengthen both the hourly and 8-hour average 

standards for CO in order to protect public health. 

We support efforts to extend the monitoring network to better capture roadside 

concentrations but believe that EPA’s proposal is insufficient to accurately 

characterize ambient CO concentrations in situations of highest exposures. 

The heart and lungs work together to deliver oxygen throughout the body and 

carbon monoxide impairs these functions. 

As EPA is well aware, NAAQS must be set at levels that will protect the public health 

with an adequate margin of safety, including the health of sensitive populations. 

This means that uncertainties must be resolved in favor of public health protection.

The standards are to be based solely on the medical evidence: considerations: what 

level of CO is safe to breathe? Standards are not to be based on estimates of risks, 

exposures, costs, or technology. And the law is clear: where there is doubt, the 

Agency must include a margin of safety. With this recommendation, that has not 

happened. 

In the case of CO, EPA has ignored the advice of its Clean Air Scientific Advisory 

Committee favoring a lower standard:
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“It is important to acknowledge the decreases in ambient CO levels over time; 

however this success should not preclude an objective assessment of the 

potential health consequences of exposures at the current CO NAAQS. While 

measured concentrations infrequently reach the current NAAQS, evidence 

indicates that adverse health effects could occur at these levels. For that 

reason, CASAC expresses its preference for a lower standard.” EPA-CASAC10-013, June 8, 2010.

The air quality standards for carbon monoxide were first established 40 years ago, 

and they have not been updated since then. 

In large part, EPA’s argument for not strengthening the standards relies on the 

assumption that concentrations (as measured at central monitoring stations) have 

been greatly reduced due to controls on motor vehicles and that the EPA exposure 

assessment indicates few “exposures of concern.”

CASAC has repeatedly advised EPA to give more consideration to the 

epidemiological studies that have reported a variety of health effects –

cardiovascular, reproductive, and respiratory occurring at contemporary 

concentrations. We agree. 

EPA’s proposal is based on outmoded assumptions that do not reflect today’s 

realities. 

In the 1970’s, concern about CO was raised in the context of urban street canyons.

Today, we have sound barriers lining major commuting routes that may have a 

similar effect in concentrating pollutants. However, we have no measurements of 

the concentrations that commuters or truck drivers might be exposed to on a daily 

basis. 

Today, we have an increase in exposures from gas-powered off-road engines that 

are poorly controlled, such as offboard motors, generators, lawnmowers, and 

construction equipment. 

Today, we are concerned about the exposures that an elderly heart patient might 

experience as they use a snowblower to clear a sidewalk surrounded by banks of 

snow. 

What about exposures that occur near to the breathing zone of gardeners, as in the 

case of gas-powered leaf blowers, chain saws, or trimmers? 

What about exposures in high-altitude areas and during the wintertime when cold 

start conditions prevail? 
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None of these are exposure scenarios are adequately addressed by the proposed 

standard. No one is adequately protected by the current standards.

Today, we are concerned about cardiovascular effects as well as neurological, 

respiratory and reproductive effects. 

We do not believe that EPA’s 2-city risk assessment that relied on central site 

monitors and considered a limited range of health endpoints and exposure 

scenarios exonerates the current standards. To the contrary, we support the 

strengthened standards as contemplated in the Policy Assessment and favored by 

CASAC. 

Additionally, we oppose any efforts to relax the form of the standard from the 

current single exceedance approach to a 99th or 98th percentile form, which would in 

effect amount to a weakening of the current standards. We oppose revocation of the 

hourly standard. 

In 2006, EPA unwisely eliminated ambient monitoring requirements for CO, except 

for the NCore network. With this proposal, EPA is proposing to partially reinstate 

the monitoring requirements in 53 large cities. 

However, this proposal is inadequate in several respects. 

First, it relies on old monitoring technology, which CASAC has stated is insufficient

to capture today’s concentrations. 

Second, a proposal to deploy 77 monitors nationwide is inadequate to capture all 

the concentrations of potential concern. 

Third, we support a coordinated effort to monitor highway air pollution, but a 

proposal this narrow can only be considered a pilot project. 

The American Lung Association recommends that the EPA not retain the nation’s 

outdated, 40-year old carbon monoxide standards. Not only do the existing 

standards fail to protect public health, they cannot possibly provide the required 

margin of safety. Instead, we recommend that EPA adopt standards that provide 

protect the requisite protection: 

We recommend retaining both the one-hour and the 8-hour averaging times 

for the standard. 

We recommend an 8-hour standard of 3 ppm using a single exceedence 

approach.

We recommend a 1-hour standard of 5 ppm using a single exceedence 

approach. 
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We recognize that these no-exceedence standards fly in the face of the drive for 

“regulatory certainty.” We disagree. The Clean Air Act provision for protecting 

public health will lead to tighter limits on this dangerous and deadly air pollutant if 

the standard recognizes that unsafe levels that finally reach the monitoring network 

indicate a serious and unacceptable situation.