Whether this range represents a continuous distribution of sensitivity within the allergic population or whether discrete highly sensitive subpopulations exist, is not known.
Sensitive subpopulations include the elderly and persons with chronic respiratory and cardiac diseases.
Ranges of exposures associated with acute sensory irritation can be derived and do include sensitive subpopulations.
The testing framework addresses risks to humans during all stages of development and provides data relevant to assessing hazards to sensitive subpopulations, such as infants and children.
"Some of the results may be of concern for potential health effects in exposed individuals, particularly in sensitive subpopulations such as children and elderly," said Serap Erdal, an associate professor of environmental and occupational health sciences at the University of Illinois at Chicago.
EPA's Clean Air Scientific Advisory Committee (CASAC) suggested a standard between 60 and 70 ppb, but it attached a big caveat to 70 ppb that it would provide "little margin of safety for the protection of public health, particularly for sensitive subpopulations".
Principle #3: Risk-Management Decisions Should Take into Account Sensitive Subpopulations.
The panel strongly advised against setting it at the higher level of 70, however, concluding that it "provides little margin of safety for the protection of public health, particularly for sensitive subpopulations".
The panel said that setting the limit at the higher end of the spectrum, at 70 parts per billion, would provide "little margin of safety for the protection of public health, particularly for sensitive subpopulations".
But the scientists strongly advised against setting the limit at the higher end of that range, saying that 70 parts per billion "provides little margin of safety for the protection of public health, particularly for sensitive subpopulations".
The panel said that setting the limit at the higher end of the spectrum, at 70 parts per billion, would provide "little margin of safety for the protection of public health, particularly for sensitive subpopulations". Setting the limit at the lower end of 60 parts per billion, however, "would certainly offer more public health protection," the committee said.
