Time Series Analysis on Relationship between Air Pollution and Outpatient Visits for Cardiovascular Diseases in a Hospital in Liu'an City

Objective  To evaluate the health effect of air pollutants on outpatient visits for cardiovascular diseases in Liu'an City.

Methods  A Generalized Additive Poisson Regression Model was used to examine the time-series and exposure-response relationship between the daily morbidity of cardiovascular diseases and the concentration of ambient SO₂, NO₂ and PM₁₀ from Jan 1, 2012 to Dec 31, 2013 in Liu'an city after controlling the effect of long-term trends of variation, such as "the day of a week" and meteorological factors.

Results  The number of daily outpatient visit for cardiovascular diseases was 69.7. The results of a single-pollutant generalized additive Poisson regression model showed a protection of SO₂ on the number of outpatient visit for cardiovascular diseases with a 3 days delay, the maximum RR for outpatient visits on each 10 μg/m³ increment of SO₂ was 0.9987 (CI:0.9975~0.9998). The increment of NO₂ and PM₁₀ concentration showed a significant increase of outpatient visit for cardiovascular diseases with a 3 days and 4 days delay, respectively. The maximum RR for daily outpatient visits on each 10 μg/m³ increment of NO₂ and PM₁₀ were 1.0022(1.0012~1.0031) and 1.00054(1.0002~1.0008), respectively.

Conclusion  The concentration of SO₂ was positively associated with daily outpatient visits; and the concentration of NO₂ and PM₁₀ was positively associated with daily outpatient visits for respiratory and cardiovascular diseases in Liu'an city.