Limits...
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

Rate ratios of emergency department visits for pediatric asthma on day following occurrence (i.e., lag 1) of each SOM-based multipollutant day type as compared to the referent group [1, 1] in Atlanta, Georgia from 1999 to 2008
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig4: Rate ratios of emergency department visits for pediatric asthma on day following occurrence (i.e., lag 1) of each SOM-based multipollutant day type as compared to the referent group [1, 1] in Atlanta, Georgia from 1999 to 2008

Mentions: The questions addressed in this section are: How does the occurrence of each type of multipollutant day observed in our study associate with the health outcome of interest? Do certain combinations associate more strongly with adverse health than others? Using MDT [1, 1] as a referent, results show significant associations with three types of days in Atlanta (Fig. 4). The strongest association (RR: 1.04, 95 % CI: 1.02, 1.05) was found for MDT [3, 2] – a type of day characterized as being generally well mixed and having above average concentrations (Fig. 2). Significant associations were also identified for MDT [3, 3] and MDT [3, 1], day types that reflect extreme concentrations for either a collection of primary pollutants (CO, NO2, NOX, EC, and OC) or a set of secondary pollutants (O3, NH4, and SO4). Collectively, these events encompassed approximately 20 % of days in our study and occurred on days when particulate matter was above average (Fig. 3). Results for MDT’s describing more typical (i.e. high frequency) air quality days ([1, 2], [2, 1]) and air quality days with single pollutant extremes ([1, 3], [2, 2]) were positive but not significant. Moderate-to-high concentration days dominated by primary pollution (MDT [2, 3]) yielded a positive estimated association but with confidence interval that includes the ; the result is intermediate between the low pollution days ([1, 2] and [2, 1]) and the high primary pollution days ([3, 3]).Fig. 4


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)

Rate ratios of emergency department visits for pediatric asthma on day following occurrence (i.e., lag 1) of each SOM-based multipollutant day type as compared to the referent group [1, 1] in Atlanta, Georgia from 1999 to 2008
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig4: Rate ratios of emergency department visits for pediatric asthma on day following occurrence (i.e., lag 1) of each SOM-based multipollutant day type as compared to the referent group [1, 1] in Atlanta, Georgia from 1999 to 2008
Mentions: The questions addressed in this section are: How does the occurrence of each type of multipollutant day observed in our study associate with the health outcome of interest? Do certain combinations associate more strongly with adverse health than others? Using MDT [1, 1] as a referent, results show significant associations with three types of days in Atlanta (Fig. 4). The strongest association (RR: 1.04, 95 % CI: 1.02, 1.05) was found for MDT [3, 2] – a type of day characterized as being generally well mixed and having above average concentrations (Fig. 2). Significant associations were also identified for MDT [3, 3] and MDT [3, 1], day types that reflect extreme concentrations for either a collection of primary pollutants (CO, NO2, NOX, EC, and OC) or a set of secondary pollutants (O3, NH4, and SO4). Collectively, these events encompassed approximately 20 % of days in our study and occurred on days when particulate matter was above average (Fig. 3). Results for MDT’s describing more typical (i.e. high frequency) air quality days ([1, 2], [2, 1]) and air quality days with single pollutant extremes ([1, 3], [2, 2]) were positive but not significant. Moderate-to-high concentration days dominated by primary pollution (MDT [2, 3]) yielded a positive estimated association but with confidence interval that includes the ; the result is intermediate between the low pollution days ([1, 2] and [2, 1]) and the high primary pollution days ([3, 3]).Fig. 4

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