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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

Seasonal frequencies, particulate matter, and meteorological summaries for the 9 multipollutant day types identified in Atlanta, GA, from January 1, 1999 to December 31, 2008. Panel a provides the seasonal frequency counts for each type. Panels b-g provide boxplots illustrating the distribution of particulate matter and meteorology under each category. Grey indicates our referent level; Light blue indicates insignificant day types; Red indicates day types significantly associated with asthma
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Fig3: Seasonal frequencies, particulate matter, and meteorological summaries for the 9 multipollutant day types identified in Atlanta, GA, from January 1, 1999 to December 31, 2008. Panel a provides the seasonal frequency counts for each type. Panels b-g provide boxplots illustrating the distribution of particulate matter and meteorology under each category. Grey indicates our referent level; Light blue indicates insignificant day types; Red indicates day types significantly associated with asthma

Mentions: We found that the most common types of days at our study location are characterized by profiles in the bottom left corner of the map (Fig. 2). The most frequent type of day (24 % of all days) in our study, MDT [1, 1], reveals that air quality conditions for Atlanta are most often well below average (i.e., the overall mean pollutant levels for Atlanta). Such relatively ‘clean’ days were found to be distributed across all seasons and were accompanied by low air pressures, higher humidity, and higher wind speed suggestive of strong atmospheric mixing and rain (Fig. 3). Another common type of day (MDT [2, 1]; 17 %) groups springtime events that entail slightly above average concentrations for secondary pollutants (O3, NH4, and SO4) and a relatively warm and stable atmosphere. MDT [1, 2] assembles cooler dry days with near to slightly above average concentrations for primary pollutants such as NO2 and NOX. Collectively, these profiles capture 57 % of days in Atlanta and thus we would consider such types to represent ‘typical’ air quality events at our study location.Fig. 3


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)

Seasonal frequencies, particulate matter, and meteorological summaries for the 9 multipollutant day types identified in Atlanta, GA, from January 1, 1999 to December 31, 2008. Panel a provides the seasonal frequency counts for each type. Panels b-g provide boxplots illustrating the distribution of particulate matter and meteorology under each category. Grey indicates our referent level; Light blue indicates insignificant day types; Red indicates day types significantly associated with asthma
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig3: Seasonal frequencies, particulate matter, and meteorological summaries for the 9 multipollutant day types identified in Atlanta, GA, from January 1, 1999 to December 31, 2008. Panel a provides the seasonal frequency counts for each type. Panels b-g provide boxplots illustrating the distribution of particulate matter and meteorology under each category. Grey indicates our referent level; Light blue indicates insignificant day types; Red indicates day types significantly associated with asthma
Mentions: We found that the most common types of days at our study location are characterized by profiles in the bottom left corner of the map (Fig. 2). The most frequent type of day (24 % of all days) in our study, MDT [1, 1], reveals that air quality conditions for Atlanta are most often well below average (i.e., the overall mean pollutant levels for Atlanta). Such relatively ‘clean’ days were found to be distributed across all seasons and were accompanied by low air pressures, higher humidity, and higher wind speed suggestive of strong atmospheric mixing and rain (Fig. 3). Another common type of day (MDT [2, 1]; 17 %) groups springtime events that entail slightly above average concentrations for secondary pollutants (O3, NH4, and SO4) and a relatively warm and stable atmosphere. MDT [1, 2] assembles cooler dry days with near to slightly above average concentrations for primary pollutants such as NO2 and NOX. Collectively, these profiles capture 57 % of days in Atlanta and thus we would consider such types to represent ‘typical’ air quality events at our study location.Fig. 3

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