Sensitivity of Ambient Atmospheric Formaldehyde and Ozone to Precursor Species and Source Types Across the United States

Abstract

Formaldehyde (HCHO) is an important air pollutant from both an atmospheric chemistry and human health standpoint. This study uses an instrumented photochemical Air Quality Model, CMAQ-DDM, to identify the sensitivity of HCHO concentrations across the United States (U.S.) to major source types and hydrocarbon speciation. In July, biogenic sources of hydrocarbons contribute the most (92% of total hydrocarbon sensitivity), split between isoprene and other alkenes. Among anthropogenic sources, mobile sources of hydrocarbons and nitrogen oxides (NO ) dominate. In January, HCHO is more sensitive to anthropogenic hydrocarbons than biogenic sources, especially mobile sources and residential wood combustion (36% of national hydrocarbon sensitivity). While ozone (O) is three times more sensitive to NO than hydrocarbons across most areas of the U.S., HCHO is six times more sensitive to hydrocarbons than NO, largely due to sensitivity to biogenic precursors and the importance of low-NO chemistry. In winter, both HCHO and O show negative sensitivity to NO (increases with the removal of NO), although O increases are larger. Relative sensitivities do not change substantially across different regions of the country.

Characterization of VOCs and their related atmospheric processes in a central Chinese city during severe ozone pollution periods

“…3, different from other months, the air current originated, with the largest portion (ca. 88.7 %), from Hubei Province; the average VOCs in its capital city (23.3 ± 0.6 ppbv) (Lyu et al, 2016) were lower than those in Zhengzhou (29.2 ± 23.1 ppbv). In combination with the lower weight percentage of photochemically reactive aromatics (10.3 ± 4.2 %), and the lowest toluene to benzene (T /B) ratio of 1.15 ± 0.99 around this period, it is possible that the cleaner air mass clusters originating from Hubei also contributed to the reduction of VOCs in July.…”

Contributions to local- and regional-scale formaldehyde concentrations

“…Sourceoriented techniques, such as the decoupled direct method (DDM; Dunker, 1981Dunker, , 1984Yang et al, 1997;Dunker et al, 2002;Hakami et al, 2003;Napelenok et al, 2006;Koo et al, 2007), require one large-scale simulation for each parameter of interest but allow for quantifying sensitivities of multiple air quality metrics at little additional cost. In contrast, receptor-oriented techniques, such as the adjoint method (Sandu et al, 2005;Martien et al, 2006;Hakami et al, 2007;Henze et al, 2007;Bastien et al, 2015), require one large-scale simulation for each air quality metric of interest but allow for the efficient calculation of sensitivities to large numbers of model parameters. While there have been numerous analyses of ozone and particulate matter, little attention has been devoted to analysis of formaldehyde mixing ratios.…”

Facile synthesis of In2O3 nanoparticles with high response to formaldehyde at low temperature

“…These materials could release formaldehyde vapor into the air . People will have adverse reactions after inhaling more than 0.1 ppm formaldehyde, such as burning sensations (eyes, nose, and throat), coughing, wheezing, and even death . The World Health Organization (WHO) has established a limit for the exposure to formaldehyde at a maximum of 0.08 ppm in 30 min on average, and the limit stipulated by the Chinese Environmental Protection Agency is 0.1 mg/m 3 .…”