Long-term dynamics of death rates of emphysema, asthma, and pneumonia and improving air quality

 

International Journal of Chronic Obstructive Pulmonary Disease

Original Research

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Authors: Kravchenko J, Akushevich I, Abernethy AP, Holman S, Ross Jr WG, Lyerly HK

Published Date June 2014 Volume 2014:9 Pages 613 - 627

DOI: http://dx.doi.org/10.2147/COPD.S59995

Received:	02 January 2014
Accepted:	09 April 2014
Published:	16 June 2014

Julia Kravchenko,¹ Igor Akushevich,² Amy P Abernethy,³ Sheila Holman,⁴ William G Ross Jr,⁵ H Kim Lyerly<sup>1,6

1</sup>Department of Surgery, ²Center for Population Health and Aging, ³Duke Clinical Research Institute, Duke University Medical Center, Duke University, Durham, ⁴Division of Air Quality, North Carolina Department of Environment and Natural Resources, Raleigh, ⁵Nicholas School of the Environment, ⁶Department of Pathology, Duke University Medical Center, Duke University, Durham, NC, USA

Background: The respiratory tract is a major target of exposure to air pollutants, and respiratory diseases are associated with both short- and long-term exposures. We hypothesized that improved air quality in North Carolina was associated with reduced rates of death from respiratory diseases in local populations.
Materials and methods: We analyzed the trends of emphysema, asthma, and pneumonia mortality and changes of the levels of ozone, sulfur dioxide (SO₂), nitrogen dioxide (NO₂), carbon monoxide (CO), and particulate matters (PM_2.5 and PM₁₀) using monthly data measurements from air-monitoring stations in North Carolina in 1993–2010. The log-linear model was used to evaluate associations between air-pollutant levels and age-adjusted death rates (per 100,000 of population) calculated for 5-year age-groups and for standard 2000 North Carolina population. The studied associations were adjusted by age group-specific smoking prevalence and seasonal fluctuations of disease-specific respiratory deaths.
Results: Decline in emphysema deaths was associated with decreasing levels of SO₂ and CO in the air, decline in asthma deaths–with lower SO₂, CO, and PM₁₀ levels, and decline in pneumonia deaths–with lower levels of SO₂. Sensitivity analyses were performed to study potential effects of the change from International Classification of Diseases (ICD)-9 to ICD-10 codes, the effects of air pollutants on mortality during summer and winter, the impact of approach when only the underlying causes of deaths were used, and when mortality and air-quality data were analyzed on the county level. In each case, the results of sensitivity analyses demonstrated stability. The importance of analysis of pneumonia as an underlying cause of death was also highlighted.
Conclusion: Significant associations were observed between decreasing death rates of emphysema, asthma, and pneumonia and decreases in levels of ambient air pollutants in North Carolina.

Keywords: chronic obstructive pulmonary disease, sulfur dioxide, carbon monoxide, nitrogen dioxide, particulate matter


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