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Exploring associations between multipollutant day types and asthma morbidity: epidemiologic applications of self-organizing map ambient air quality classifications.

Pearce JL, Waller LA, Mulholland JA, Sarnat SE, Strickland MJ, Chang HH, Tolbert PE - Environ Health (2015)

Bottom Line: Recent interest in the health effects of air pollution focuses on identifying combinations of multiple pollutants that may be associated with adverse health risks.Using a low pollution day type as the reference level, we found significant associations of increased asthma morbidity in three of nine categories suggesting adverse effects when combinations of primary (CO, NO2, NOX, EC, and OC) and/or secondary (O3, NH4, SO4) pollutants exhibited elevated concentrations (typically, occurring on dry days with low wind speed).We found that ED visits for pediatric asthma in Atlanta were more strongly associated with certain day types defined by multipollutant characteristics than days with low pollution levels; however, findings did not suggest that any specific combinations were more harmful than others.

View Article: PubMed Central - PubMed

Affiliation: Department of Public Health Sciences, College of Medicine, Medical University of South Carolina, 135 Cannon Street, Charleston, SC, 29422, United States. pearcejo@musc.edu.

ABSTRACT

Background: Recent interest in the health effects of air pollution focuses on identifying combinations of multiple pollutants that may be associated with adverse health risks.

Objective: Present a methodology allowing health investigators to explore associations between categories of ambient air quality days (i.e., multipollutant day types) and adverse health.

Methods: First, we applied a self-organizing map (SOM) to daily air quality data for 10 pollutants collected between January 1999 and December 2008 at a central monitoring location in Atlanta, Georgia to define a collection of multipollutant day types. Next, we conducted an epidemiologic analysis using our categories as a multipollutant metric of ambient air quality and daily counts of emergency department (ED) visits for asthma or wheeze among children aged 5 to 17 as the health endpoint. We estimated rate ratios (RR) for the association of multipollutant day types and pediatric asthma ED visits using a Poisson generalized linear model controlling for long-term, seasonal, and weekday trends and weather.

Results: Using a low pollution day type as the reference level, we found significant associations of increased asthma morbidity in three of nine categories suggesting adverse effects when combinations of primary (CO, NO2, NOX, EC, and OC) and/or secondary (O3, NH4, SO4) pollutants exhibited elevated concentrations (typically, occurring on dry days with low wind speed). On days with only NO3 elevated (which tended to be relatively cool) and on days when only SO2 was elevated (which likely reflected plume touchdowns from coal combustion point sources), estimated associations were modestly positive but confidence intervals included the .

Conclusions: We found that ED visits for pediatric asthma in Atlanta were more strongly associated with certain day types defined by multipollutant characteristics than days with low pollution levels; however, findings did not suggest that any specific combinations were more harmful than others. Relative to other health endpoints, asthma exacerbation may be driven more by total ambient pollutant exposure than by composition.

No MeSH data available.


Related in: MedlinePlus

A 3 × 3 SOM of 9 multipollutant day types observed in Atlanta, GA, from January 1, 1999 to December 31, 2008. For each type, profile bars reflect the average (±SD) pollutant concentrations on assigned days zeroed to the overall mean on a percentage scale. Coordinate labels are in brackets [] and the relative frequencies (%) and within-class sample size (n) are presented in the upper right hand corner of each panel
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Fig2: A 3 × 3 SOM of 9 multipollutant day types observed in Atlanta, GA, from January 1, 1999 to December 31, 2008. For each type, profile bars reflect the average (±SD) pollutant concentrations on assigned days zeroed to the overall mean on a percentage scale. Coordinate labels are in brackets [] and the relative frequencies (%) and within-class sample size (n) are presented in the upper right hand corner of each panel

Mentions: To answer our first set of proposed questions we present a 3x3 SOM that illustrates ambient air quality using 9 categories of days that reflect the range of multipollutant events frequently observed at our monitoring location (Fig. 2). Each category is described as a multipollutant day type (MDT) and is referenced using SOM [x,y] coordinates. Furthermore, MDT profiles are displayed as barplots that present mean centered values on a percentage scale along with their standard deviations. For summary statistics of the SOM see Table 1.Fig. 2


Exploring associations between multipollutant day types and asthma morbidity: epidemiologic applications of self-organizing map ambient air quality classifications.

Pearce JL, Waller LA, Mulholland JA, Sarnat SE, Strickland MJ, Chang HH, Tolbert PE - Environ Health (2015)

A 3 × 3 SOM of 9 multipollutant day types observed in Atlanta, GA, from January 1, 1999 to December 31, 2008. For each type, profile bars reflect the average (±SD) pollutant concentrations on assigned days zeroed to the overall mean on a percentage scale. Coordinate labels are in brackets [] and the relative frequencies (%) and within-class sample size (n) are presented in the upper right hand corner of each panel
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4477305&req=5

Fig2: A 3 × 3 SOM of 9 multipollutant day types observed in Atlanta, GA, from January 1, 1999 to December 31, 2008. For each type, profile bars reflect the average (±SD) pollutant concentrations on assigned days zeroed to the overall mean on a percentage scale. Coordinate labels are in brackets [] and the relative frequencies (%) and within-class sample size (n) are presented in the upper right hand corner of each panel
Mentions: To answer our first set of proposed questions we present a 3x3 SOM that illustrates ambient air quality using 9 categories of days that reflect the range of multipollutant events frequently observed at our monitoring location (Fig. 2). Each category is described as a multipollutant day type (MDT) and is referenced using SOM [x,y] coordinates. Furthermore, MDT profiles are displayed as barplots that present mean centered values on a percentage scale along with their standard deviations. For summary statistics of the SOM see Table 1.Fig. 2

Bottom Line: Recent interest in the health effects of air pollution focuses on identifying combinations of multiple pollutants that may be associated with adverse health risks.Using a low pollution day type as the reference level, we found significant associations of increased asthma morbidity in three of nine categories suggesting adverse effects when combinations of primary (CO, NO2, NOX, EC, and OC) and/or secondary (O3, NH4, SO4) pollutants exhibited elevated concentrations (typically, occurring on dry days with low wind speed).We found that ED visits for pediatric asthma in Atlanta were more strongly associated with certain day types defined by multipollutant characteristics than days with low pollution levels; however, findings did not suggest that any specific combinations were more harmful than others.

View Article: PubMed Central - PubMed

Affiliation: Department of Public Health Sciences, College of Medicine, Medical University of South Carolina, 135 Cannon Street, Charleston, SC, 29422, United States. pearcejo@musc.edu.

ABSTRACT

Background: Recent interest in the health effects of air pollution focuses on identifying combinations of multiple pollutants that may be associated with adverse health risks.

Objective: Present a methodology allowing health investigators to explore associations between categories of ambient air quality days (i.e., multipollutant day types) and adverse health.

Methods: First, we applied a self-organizing map (SOM) to daily air quality data for 10 pollutants collected between January 1999 and December 2008 at a central monitoring location in Atlanta, Georgia to define a collection of multipollutant day types. Next, we conducted an epidemiologic analysis using our categories as a multipollutant metric of ambient air quality and daily counts of emergency department (ED) visits for asthma or wheeze among children aged 5 to 17 as the health endpoint. We estimated rate ratios (RR) for the association of multipollutant day types and pediatric asthma ED visits using a Poisson generalized linear model controlling for long-term, seasonal, and weekday trends and weather.

Results: Using a low pollution day type as the reference level, we found significant associations of increased asthma morbidity in three of nine categories suggesting adverse effects when combinations of primary (CO, NO2, NOX, EC, and OC) and/or secondary (O3, NH4, SO4) pollutants exhibited elevated concentrations (typically, occurring on dry days with low wind speed). On days with only NO3 elevated (which tended to be relatively cool) and on days when only SO2 was elevated (which likely reflected plume touchdowns from coal combustion point sources), estimated associations were modestly positive but confidence intervals included the .

Conclusions: We found that ED visits for pediatric asthma in Atlanta were more strongly associated with certain day types defined by multipollutant characteristics than days with low pollution levels; however, findings did not suggest that any specific combinations were more harmful than others. Relative to other health endpoints, asthma exacerbation may be driven more by total ambient pollutant exposure than by composition.

No MeSH data available.


Related in: MedlinePlus