Search Results

You are looking at 1 - 10 of 16,726 items for :

  • Air quality x
  • Refine by Access: All Content x
Clear All
Huiling Ouyang
,
Xu Tang
,
Rajesh Kumar
,
Renhe Zhang
,
Guy Brasseur
,
Ben Churchill
,
Mozaharul Alam
,
Haidong Kan
,
Hong Liao
,
Tong Zhu
,
Emily Ying Yang Chan
,
Ranjeet Sokhi
,
Jiacan Yuan
,
Alexander Baklanov
,
Jianmin Chen
, and
Maria Katherina Patdu

On 22 September 2021, the World Health Organization (WHO) launched new Global Air Quality Guidelines (AQGs) to address this worldwide issue ( WHO 2021a ). Except for SO 2 , all the other 2021 AQGs are considerably stricter than the 2005 WHO AQGs and several new indices have also been developed ( Table 1 ). Recent advances in epidemiological and cohort studies have provided strong evidence that the adverse effects of air pollution can be observed not only at high exposure concentrations but

Full access
Tanya L. Otte

1. Introduction Complex, limited-area, multipollutant air quality models typically obtain meteorological fields from Eulerian (gridded) meteorological models. It is well known that the meteorological conditions exert a significant influence on air quality (e.g., Flaum et al. 1996 ; Milanchus et al. 1998 ). For nearly two decades, there has been a great interest in assessing the impact that meteorological modeled fields have on air quality model simulations. Pielke and Uliasz (1998) and

Full access
Tanya L. Otte

1. Introduction For two decades, limited-area Eulerian (or gridded) air quality models have been forced by meteorological fields that are generated by Eulerian meteorological models, in part, because meteorological observations and archived forecast fields do not exist at high enough temporal and spatial resolutions to capture atmospheric variables (e.g., mixing depth, column temperature, and wind profiles) that are important for regional-scale chemical transport modeling. Meteorological models

Full access
S. Kondragunta
,
P. Lee
,
J. McQueen
,
C. Kittaka
,
A. I. Prados
,
P. Ciren
,
I. Laszlo
,
R. B. Pierce
,
R. Hoff
, and
J. J. Szykman

1. Introduction Congressional mandate (H. R. 4. Energy Act of 2002) required the National Oceanic and Atmospheric Administration (NOAA) National Weather Service (NWS) to develop and deploy an air quality modeling system capable of issuing nationwide hourly ozone and PM2.5 (particles smaller than 2.5 μ m in median diameter) forecast guidance. In response to the mandate, NOAA has developed an air quality forecast capability in partnership with the U.S. Environmental Protection Agency (EPA). The

Full access
Zhan Zhao
,
Shu-Hua Chen
,
Michael J. Kleeman
,
Mary Tyree
, and
Dan Cayan

(SoCAB) ( Fig. 1a ). The annual average PM 2.5 concentration in SJV and SoCAB were 21.5 μ g m −3 and 19.7 μ g m −3 , respectively, during 2007/08. These concentrations were the highest nationwide ( Mahmud et al. 2010 ) and were much higher than the current National Ambient Air Quality Standard of 15 μ g m −3 . In the years 2005–07, all of the “top six” counties with the highest O 3 concentrations over the entire United States were located in SJV and SoCAB ( Howard et al. 2010 ). The pollutants

Full access
Zhan Zhao
,
Shu-Hua Chen
,
Michael J. Kleeman
, and
Abdullah Mahmud

1. Introduction The Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report ( Solomon et al. 2007 ) states that “most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.” Temperature is a decisive meteorological variable for regional climate and air quality. A temperature change can result in a change in atmospheric and oceanic circulations ( Nitta and

Full access
Stephen F. Mueller

1. Introduction Air quality models are used extensively for environmental planning and determining compliance with air quality regulations. Model performance is typically evaluated against observations. As described by regulatory guidance issued by the U.S. Environmental Protection Agency (EPA), various error metrics are considered valuable for determining the ability of a model to capture accurately the important links between emissions and levels of air pollutants ( U.S. EPA 2007 ). All of

Full access
Scott Beaver
,
Saffet Tanrikulu
,
Ahmet Palazoglu
,
Angadh Singh
,
Su-Tzai Soong
,
Yiqin Jia
,
Cuong Tran
,
Bruce Ainslie
, and
Douw G. Steyn

1. Introduction Photochemical air quality model (AQM; Russell and Dennis 2000 ) simulations are increasingly used for regulatory purposes ( Fine et al. 2003 ). They provide technical information to support air quality planning decisions. The resulting policies can affect billions of dollars worth of public health and economic activity annually ( Yang et al. 2005 ). Because of the large stakes involved, policy makers require confidence that simulation results are valid. For use in policy making

Full access
Daiwen Kang
,
Rohit Mathur
,
Kenneth Schere
,
Shaocai Yu
, and
Brian Eder

1. Introduction The skill of an air quality forecast system is gauged by how well the modeling system predicts species concentrations in relation to threshold values. These events, which are referred to as “exceedances” and “nonexceedances,” can be evaluated using categorical metrics. Current categorical metrics used in model evaluations (e.g., Kang et al. 2005 ) measure the model’s ability to predict an exceedance using a fixed threshold mixing ratio (or “clear cut”), and the metrics are

Full access
Hye-Ryun Oh
,
Chang-Hoi Ho
,
Doo-Sun R. Park
,
Jinwon Kim
,
Chang-Keun Song
, and
Sun-Kyong Hur

( Baek and Koo 2008 ; Gyeonggi Research Institute 2011 ). The government invested approximately 4 trillion South Korean won 1 in the act for the first 10 years. The second phase of the 10-Year Act commenced in 2015 ( http://eng.me.go.kr/eng/web/index.do?menuId=238 ). It includes various air quality control strategies, such as enforcing the installation of particulate filters in diesel engines, encouraging the use of eco-friendly (i.e., hybrid and electric) cars, and increasing air pollutant

Full access