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Tempo-Spatial Variations of Ambient Ozone-Mortality Associations in the USA: Results from the NMMAPS Data

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ABSTRACT

Although the health effects of ambient ozone have been widely assessed, their tempo-spatial variations remain unclear. We selected 20 communities (ten each from southern and northern USA) based on the US National Morbidity, Mortality, and Air Pollution Study (NMMAPS) dataset. A generalized linear model (GLM) was used to estimate the season-specific association between each 10 ppb (lag0-2 day average) increment in daily 8 h maximum ozone concentration and mortality in every community. The results showed that in the southern communities, a 10 ppb increment in ozone was linked to an increment of mortality of −0.07%, −0.17%, 0.40% and 0.27% in spring, summer, autumn and winter, respectively. For the northern communities, the excess risks (ERs) were 0.74%, 1.21%, 0.52% and −0.65% in the spring, summer, autumn and winter seasons, respectively. City-specific ozone-related mortality effects were positively related with latitude, but negatively related with seasonal average temperature in the spring, summer and autumn seasons. However, a reverse relationship was found in the winter. We concluded that there were different seasonal patterns of ozone effects on mortality between southern and northern US communities. Latitude and seasonal average temperature were identified as modifiers of the ambient ozone-related mortality risks.

No MeSH data available.


Sensitivity analysis on the effects of ozone on mortality with different df of smoothness of time per year. Note: All ERs were adjusted for daily TM, time, day of week and RH. National Morbidity Mortality and Air Pollution Study (NMMAPS) database.
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ijerph-13-00851-f004: Sensitivity analysis on the effects of ozone on mortality with different df of smoothness of time per year. Note: All ERs were adjusted for daily TM, time, day of week and RH. National Morbidity Mortality and Air Pollution Study (NMMAPS) database.

Mentions: Sensitivity analyses indicate that the results were generally robust to changing the df of smoothness of time per year, but there is an exception (Figure 4). In the analysis that examined the effect of ozone on mortality in the winter of southern communities, the ER for each 10 ppb increment in ozone concentration significantly increased from 0.27% (95% CI: −0.15% ~ 0.07%) to 1.89% (95% CI: 1.26% ~ 2.54%) when changing the df from 7 to 8 per year. However, the ER did not change significantly when changing the df of time in the range of 5–7 per year. We did not find significant changes of ozone effects when altering the lag days of ozone exposure (lag0-1, lag0-2 and lag0-3), either. We observed similar seasonal and regional patterns of ozone effects in the communities with the maximum concentrations at both northern and southern regions. For example, a significant effect of ozone on mortality was observed in the autumn season of Dallas (southern community) and in the summer season of Washington (norther community) (Table S3).


Tempo-Spatial Variations of Ambient Ozone-Mortality Associations in the USA: Results from the NMMAPS Data
Sensitivity analysis on the effects of ozone on mortality with different df of smoothness of time per year. Note: All ERs were adjusted for daily TM, time, day of week and RH. National Morbidity Mortality and Air Pollution Study (NMMAPS) database.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036684&req=5

ijerph-13-00851-f004: Sensitivity analysis on the effects of ozone on mortality with different df of smoothness of time per year. Note: All ERs were adjusted for daily TM, time, day of week and RH. National Morbidity Mortality and Air Pollution Study (NMMAPS) database.
Mentions: Sensitivity analyses indicate that the results were generally robust to changing the df of smoothness of time per year, but there is an exception (Figure 4). In the analysis that examined the effect of ozone on mortality in the winter of southern communities, the ER for each 10 ppb increment in ozone concentration significantly increased from 0.27% (95% CI: −0.15% ~ 0.07%) to 1.89% (95% CI: 1.26% ~ 2.54%) when changing the df from 7 to 8 per year. However, the ER did not change significantly when changing the df of time in the range of 5–7 per year. We did not find significant changes of ozone effects when altering the lag days of ozone exposure (lag0-1, lag0-2 and lag0-3), either. We observed similar seasonal and regional patterns of ozone effects in the communities with the maximum concentrations at both northern and southern regions. For example, a significant effect of ozone on mortality was observed in the autumn season of Dallas (southern community) and in the summer season of Washington (norther community) (Table S3).

View Article: PubMed Central - PubMed

ABSTRACT

Although the health effects of ambient ozone have been widely assessed, their tempo-spatial variations remain unclear. We selected 20 communities (ten each from southern and northern USA) based on the US National Morbidity, Mortality, and Air Pollution Study (NMMAPS) dataset. A generalized linear model (GLM) was used to estimate the season-specific association between each 10 ppb (lag0-2 day average) increment in daily 8 h maximum ozone concentration and mortality in every community. The results showed that in the southern communities, a 10 ppb increment in ozone was linked to an increment of mortality of −0.07%, −0.17%, 0.40% and 0.27% in spring, summer, autumn and winter, respectively. For the northern communities, the excess risks (ERs) were 0.74%, 1.21%, 0.52% and −0.65% in the spring, summer, autumn and winter seasons, respectively. City-specific ozone-related mortality effects were positively related with latitude, but negatively related with seasonal average temperature in the spring, summer and autumn seasons. However, a reverse relationship was found in the winter. We concluded that there were different seasonal patterns of ozone effects on mortality between southern and northern US communities. Latitude and seasonal average temperature were identified as modifiers of the ambient ozone-related mortality risks.

No MeSH data available.