Chapter 4
Sensitivity of Ambient Atmospheric
Formaldehyde to VOC and NO x
Emissions: Implications for Predicting
Multi-pollutant Benefits of Emission
Reductions
Deborah Luecken and Sergey Napelenok
Abstract This study uses a photochemical Air Quality Model applied across the
continental US to identify source categories and chemical species (hydrocarbons and
nitrogen oxides) that have the largest impact on concentrations of ambient formaldehyde. We contrast the sensitivities of formaldehyde to those of ozone. Although reactions of organic radicals with nitrogen oxide can produce high yields of formaldehyde, the concentrations are more sensitive to hydrocarbons. Biogenic sources of
hydrocarbons contribute the most to formaldehyde sensitivity in July, with contributions from isoprene, other alkenes and direct emissions. These results indicate
that different strategies may be needed to reduce ambient ozone and formaldehyde
concentrations.
4.1 Introduction
Formaldehyde (HCHO) is a ubiquitous trace chemical in the troposphere which plays
an important role in atmospheric photochemistry because it reacts quickly and provides a major source of new radicals which drives ozone (O 3 ) production. HCHO
also is important per se because it can adversely impact human health: inhalation
exposure causes upper airway irritation and it is a probable human carcinogen [7].
In national studies of risk from 187 Hazardous Air Pollutants (HAPs), HCHO contributes over half of total cancer risk, and 9% of noncancer risk, making it a national
risk driver in 99% of US census tracts [5].
HCHO is emitted from many sources, with fuel combustion activities being predominant anthropogenic sources. HCHO also is produced in the atmosphere from
emissions of almost every organic hydrocarbon. Unraveling the role of these two
D. Luecken (B) · S. Napelenok
U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
e-mail: luecken.deborah@epa.gov
S. Napelenok
e-mail: napelenok.sergey@epa.gov
This is a U.S. government work and not under copyright protection in the U.S.; foreign
copyright protection may apply 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity, https://doi.org/10.1007/978-3-030-22055-6_4
23
Sensitivity of Ambient Atmospheric
Formaldehyde to VOC and NO x
Emissions: Implications for Predicting
Multi-pollutant Benefits of Emission
Reductions
Deborah Luecken and Sergey Napelenok
Abstract This study uses a photochemical Air Quality Model applied across the
continental US to identify source categories and chemical species (hydrocarbons and
nitrogen oxides) that have the largest impact on concentrations of ambient formaldehyde. We contrast the sensitivities of formaldehyde to those of ozone. Although reactions of organic radicals with nitrogen oxide can produce high yields of formaldehyde, the concentrations are more sensitive to hydrocarbons. Biogenic sources of
hydrocarbons contribute the most to formaldehyde sensitivity in July, with contributions from isoprene, other alkenes and direct emissions. These results indicate
that different strategies may be needed to reduce ambient ozone and formaldehyde
concentrations.
4.1 Introduction
Formaldehyde (HCHO) is a ubiquitous trace chemical in the troposphere which plays
an important role in atmospheric photochemistry because it reacts quickly and provides a major source of new radicals which drives ozone (O 3 ) production. HCHO
also is important per se because it can adversely impact human health: inhalation
exposure causes upper airway irritation and it is a probable human carcinogen [7].
In national studies of risk from 187 Hazardous Air Pollutants (HAPs), HCHO contributes over half of total cancer risk, and 9% of noncancer risk, making it a national
risk driver in 99% of US census tracts [5].
HCHO is emitted from many sources, with fuel combustion activities being predominant anthropogenic sources. HCHO also is produced in the atmosphere from
emissions of almost every organic hydrocarbon. Unraveling the role of these two
D. Luecken (B) · S. Napelenok
U.S. Environmental Protection Agency, Research Triangle Park, NC, USA
e-mail: luecken.deborah@epa.gov
S. Napelenok
e-mail: napelenok.sergey@epa.gov
This is a U.S. government work and not under copyright protection in the U.S.; foreign
copyright protection may apply 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity, https://doi.org/10.1007/978-3-030-22055-6_4
23