2010 Progress Report - International Joint Commission

such as premature mortality, hospital admissions or
emergency department visits for cardiopulmonary
diseases, increased respiratory symptoms, decreased
lung function, and physiological changes or biomarkers
for cardiac changes. Long-term exposure to fi ne
particles has also been associated with mortality
from cardiopulmonary diseases and lung cancer and
effects on the respiratory system, such as decreased
lung function and chronic respiratory disease.
There are several sensitive or vulnerable subpopulations
that appear to be at greater risk to PM-related effects.
These include individuals with preexisting heart and
lung disease, older adults and children.
U.S. Report on Health Effects
of NO 2
The health effects of NO 2
have been documented
and critically assessed in the U.S. Environmental
Protection Agency’s Integrated Science Assessment
for Oxides of Nitrogen—Health Criteria (ISA). NO 2
-
associated exposures and health risks have been
assessed in the Risk and Exposure Assessment to
Support the Review of the NO 2
Primary National
Ambient Air Quality Standard (REA). 3 The purpose
of the ISA was to critically evaluate and assess
available scientifi c information to inform the review
of the NO 2
NAAQS, while the REA presents analyses
of NO 2
-associated exposures and health risks as
well as an assessment of potential policy options for
consideration with regard to the NO 2
primary NAAQS.
The ISA has concluded that the fi ndings of
epidemiological, controlled human exposure, and
animal toxicological studies provide evidence that is
suffi cient to infer a likely causal relationship between
respiratory effects and short-term (1–24 hours)
NO 2
exposure. The strongest evidence for such a
relationship comes from epidemiological studies of
respiratory effects including symptoms, emergency
department visits and hospital admissions. A number
of these studies, most of which were published after
the previous review of the NO 2
NAAQS (completed
in 1996), have reported associations between shortterm
ambient NO 2
concentrations and respiratory
morbidity in locations with NO 2
concentrations below
those allowed by the then-current NO 2
NAAQS.
Epidemiological studies are supported by evidence
from experimental studies, including controlled
human exposure studies that evaluate airway hyperresponsiveness
in asthmatic individuals. Enhanced
airway responsiveness could have important clinical
implications for asthmatics since transient increases
in airway responsiveness following NO 2
exposure
have the potential to increase symptoms and worsen
asthma control. Overall, the ISA concluded that the
epidemiological and experimental data sets form a
plausible, consistent and coherent description of a
relationship between NO 2
exposures and an array of
adverse health effects that range from the onset of
respiratory symptoms to hospital admission.
Scientific and Technical Cooperation and Research
3
The fi nal ISA and REA can be accessed at http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=194645 and
http://www.epa.gov/ttn/naaqs/standards/nox/data/20081121_NO2_REA_fi nal.pdf, respectively.
57