scholarly journals Four Decades of United States Mobile Source Pollutants: Spatial–Temporal Trends Assessed by Ground-Based Monitors, Air Quality Models, and Satellites

2021 ◽  
Author(s):  
Lucas R. F. Henneman ◽  
Huizhong Shen ◽  
Christian Hogrefe ◽  
Armistead G. Russell ◽  
Corwin M. Zigler
Keyword(s):  
United States ◽  
Air Quality ◽  
Temporal Trends ◽  
Mobile Source ◽  
Quality Models

scholarly journals Have improvements in ozone air quality reduced ozone uptake into plants?

Elem Sci Anth ◽  
2020 ◽  
Vol 8 ◽  
Author(s):  
Allison C. Ronan ◽  
Jason A. Ducker ◽  
Jordan L. Schnell ◽  
Christopher D. Holmes
Keyword(s):  
United States ◽  
Air Quality ◽  
Plant Uptake ◽  
Environmental Variability ◽  
Statistical Tests ◽  
Temporal Trends ◽  
The United States ◽  
Cumulative Exposure ◽  
Plant Injury ◽  
Incomplete Picture

Peak levels of ozone (O3)—quantified by concentration metrics such as accumulated O3 exposure over a threshold of 40 ppb (AOT40) and the sigmoidal-weighted cumulative exposure (W126)—have decreased over large parts of the United States and Europe in the last several decades. Past studies have suggested that these improvements in AOT40 and W126 indicate reductions in plant injury, even though it is widely recognized that O3 flux into leaves, not ambient O3 concentration, is the cause of plant damage. Using a new dataset of O3 uptake into plants derived from eddy covariance flux towers, we test whether AOT40, W126, or summer mean O3 are useful indicators of trends in the cumulative uptake of O3 into leaves, which is the phytotoxic O3 dose (POD or PODy, where y is a detoxification threshold). At 32 sites in the United States and Europe, we find that the AOT40 and W126 concentration metrics decreased over 2005–2014 at most sites: 25 and 28 sites, respectively. POD0, however, increased at a majority (18) of the sites. Multiple statistical tests demonstrate that none of the concentration metrics—AOT40, W126, and mean O3—are good predictors of POD0 temporal trends or variability (R2 ≤ 0.15). These results are insensitive to using a detoxification threshold (POD3). The divergent trends for O3 concentration and plant uptake are due to stomatal control of flux, which is shaped by environmental variability and plant factors. As a result, there has been no widespread, clear improvement in POD over 2005–2014 at the sites we can assess. Decreases in concentration metrics, therefore, give an overly optimistic and incomplete picture of the direction and magnitude of O3 impacts on vegetation. Because of this lack of relation between O3 flux and concentration, flux metrics should be preferred over concentration metrics in assessments of plant injury from O3.

Protecting Air Quality

2019 ◽  
pp. 154-188
Author(s):  
David Vogel
Keyword(s):  
United States ◽  
Air Quality ◽  
Los Angeles ◽  
Pollution Control ◽  
The United States ◽  
Motor Vehicles ◽  
Air Pollution Control ◽  
Mobile Source ◽  
Progressive Development ◽  
Regulatory Capacity

This chapter looks at the efforts to protect California's air quality. Public and business demands for automobile control in the United States originated in Los Angeles, and pollution controls for motor vehicles were essentially initiated by the state of California. Following a successful national political campaign that pitted the interests of California against the nation's automotive manufacturers, in 1967, Congress allowed California—and initially only California—to issue its own vehicle emissions standards. Thanks to the unique pollution problems of Los Angeles, the United States became and remains the only country to have two distinctive mobile-source pollution control standards. Many of the themes described throughout this book are illustrated in this chapter. These include the importance of both citizen mobilization and business support for stronger environmental regulations and the progressive development of the state's regulatory capacity, from the creation of the Smoke and Fumes Commission in Los Angeles in 1945 to the organization of air pollution control districts in 1947 and finally the establishment in 1968 of the California Air Resources Board.

Monitoring air quality in class I wilderness areas of the northeastern United States using lichens and bryophytes

2016 ◽  
Author(s):  
Alison C. Dibble ◽  
James W. Hinds ◽  
Ralph Perron ◽  
Natalie Cleavitt ◽  
Richard L. Poirot ◽  
...  
Keyword(s):  
United States ◽  
Air Quality ◽  
Class I ◽  
Northeastern United States ◽  
Wilderness Areas
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