Thursday, October 8, 2015

The "Weather Penalty":How Does It Affect the Health Impact of Air Pollution?

The impact of weather changes on air quality and health in the United States in 1994–2012 (12 page pdf, Iny Jhun, BrentACoull, Joel Schwartz, Bryan Hubbell and Petros Koutrakis, Environ. Res. Lett., Aug. 12, 2015)

Today we review research in to the ways that various weather parameters affects air quality and what this means in terms of additional deaths, as analyzed over a period of eight years in the USA. Windspeed and temperature were considered the most important. Results indicate that often a given parameter has opposite effects on the degree of air pollution- for example, warmer temperatures can both increase and reduce the production of ozone. The annual average weather penalty was estimated as 290 deaths due to O3 and 770 deaths related to PM.  
o3 and pm and weather 
Key Quotes:

“O3 primarily results from reactions between nitrogen oxides and volatile organic compounds in the presence of sunlight, and high temperature, low humidity, and low wind speed conditions favor O3 formation”

Weather impacts onPM2.5 can be more variable, given the diversity of particle components (e.g., sulfate, nitrate, organic carbon, and elemental carbon). In general, particles are efficiently scavenged through wet deposition”

“Water vapor has competing effects onO3 concentrations by facilitating hydroxyl radical production from O3 photolysis, which can collectively yield a net O3 loss (via photolysis) or netO3 production (via hydroxyl radical chemistry).”

“Decreases in wind speed were consistently associated withO3 increases in the warm season. Low wind speed and high ambient temperature are conditions characteristic of stagnation leading to favorable conditions for O3 formation during the summertime”

“In summary, much of the weather penalty on O3 can be attributed to changes in temperature and water vapor pressure, but the significant decline in windspeeds also contributed to the warm season O3 penalty.”

“Temperature and wind speed were the most important determinants of PM2.5 concentrations and trends in most regions…Temperature increases can have opposing effects on PM2.5 by increasing sulfate concentrations through increased oxidation and decreasing nitrate levels due to ammonium nitrate volatilization”

 “weather-related penalty on air quality had the greatest mortality impacts in the Eastern US (NE, SE, and IM), where both population size and weather penalties were highest.. The weather penalty was associated with 290 annual deaths related to O3 and 770 annual deaths related to PM2.5.”

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