1 research outputs found
Photochemical Conversion of Surrogate Emissions for Use in Toxicological Studies: Role of Particulate- and Gas-Phase Products
The production of photochemical atmospheres
under controlled conditions
in an irradiation chamber permits the manipulation of parameters that
influence the resulting air-pollutant chemistry and potential biological
effects. To date, no studies have examined how contrasting atmospheres
with a similar Air Quality Health Index (AQHI), but with differing
ratios of criteria air pollutants, might differentially affect health
end points. Here, we produced two atmospheres with similar AQHIs based
on the final concentrations of ozone, nitrogen dioxide, and particulate
matter (PM<sub>2.5</sub>). One simulated atmosphere (SA-PM) generated
from irradiation of ∼23 ppmC gasoline, 5 ppmC α-pinene,
529 ppb NO, and 3 μg m<sup>–3</sup> (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> as a seed resulted in an average of 976 μg
m<sup>–3</sup> PM<sub>2.5</sub>, 326 ppb NO<sub>2</sub>, and
141 ppb O<sub>3</sub> (AQHI 97.7). The other atmosphere (SA-O<sub>3</sub>) generated from 8 ppmC gasoline, 5 ppmC isoprene, 874 ppb
NO, and 2 μg m<sup>–3</sup> (NH<sub>4</sub>)<sub>2</sub>SO<sub>4</sub> resulted in an average of 55 μg m<sup>–3</sup> PM<sub>2.5</sub>, 643 ppb NO<sub>2</sub>, and 430 ppb O<sub>3</sub> (AQHI of 99.8). Chemical speciation by gas chromatography showed
that photo-oxidation degraded the organic precursors and promoted
the de novo formation of secondary reaction products such as formaldehyde
and acrolein. Further work in accompanying papers describe toxicological
outcomes from the two distinct photochemical atmospheres