Impact Of Temperature Change And Ciculation Weather Types On Hospital Admissions For Chronic Obstructive Pulmonary Disease In Changchun,China

Numerousstudies have found that temperature-related environment variables are associated with respiratory diseases and mortality.It can be suggested that low ambient daily temperaturecauses a mild inflammatory reaction and a deterioration of patients’condition,and their immune function may decrease in response to a sharp decrease or increase in temperature.There are obvious connections between respiratory diseases and type of atmospheric weather conditionin winter.In the current study,we investigated the association between atmospheric condition and the Chronic Obstructive Pulmonary Disease（COPD）using daily data of hospitalized cases of COPD duringJanuary 1^st,2009 to December 31^st,2012 and simultaneous daily meteorological datain Changchun,China.Based on Generalized Additive Model（GAM）,the effectsof ambient daily temperature,diurnal temperature range（DTR）and temperature change in24 hours（T24）were expressed asrelative risk values（RRs）of COPDwith 95%Confidence Intervals（CIs）with per 1°C increase in ambient daily temperature,DTR and T24.To analyse the possible links between daily hospital admissions and weather conditions along with its delayed effects,we used meteorological data and hospital admissions data associated with the Lamb-Jenkinson classification of weather types.Lastly,we choose a representative example to study the effects of cold spell on hospital admissions due to COPD in Changchun.The main results are as follows:The results reveal that there are monthly and seasonal variations of number of patients with COPD.Specifically,the number of patients is the highest in spring,and the lowest in summer.Modification effectof gender shows that women have a higher morbidity than men,whilemodifying effect of ageindicatesthe elderly are more vulnerable than the non-elderly.These findings also support the hypothesis of a positive association between COPD hospital admissions and DTR,wind speed in Changchun,China,along with an inverse relationship between the admissions and relative humidity.The results analyzed by Generalized Additive Model（GAM）showed that both the lower and higher temperature did not show remarkable influences to COPD,while the effects were significantduring the transition from spring to summer,and summer to autumn.The relative risks of COPD were significantly increased with an increaseof 1°C in DTR,modified by season,age and sex.A season-specific effect wasalso detected for temperature change within 24 hours.The relative risk values with per 1°C change in temperature within 24hours were greater in warm season than in cold seasonon people other than males,and the effects of temperature risewithin 24 hours were greater than temperature drop on people other than non-elderly during the same season.Overall,when temperature drops in 24 hours,the greater estimates for non-elderly appeared at lag 3 days,with RR of 1.039（0.999,1.081）.When temperature rises in 24 hours,the greatest RR was reached 1.037（1.000,1.076）at lag 7 for women.An automatic classification scheme of the atmospheric circulation affecting Changchun,China,between 2009 and 2012,is presented.Daily circulation is represented by a set of indices associated with the direction and vorticity of the near-surface flow.The statistics of atmospheric circulation patterns in Changchun during 2009-2012 revealed that the more frequentsituation is Cyclone（C）type.Cyclone cases are the most frequent,with maxima occurring in the summer months,accounting for more than one-sixth of time series.The second high frequency is Westerly（W）,followed byNortherly（N）,Southwesterly（SW）,and Anticyclone（A）circulations.Above six types accounted formore than half of the total days.In general,the cyclonic circulation and the southerly airflow pattern mostly occurred during the warm season.The results show that hospital admissions for COPD rise obviously under the weather types associated with cold,dry,high pressure and temperature drop,such as hybrid anticyclone in which northly flow dominating.Weaker effects of circulation weather types onhospital admissionsare associatedwith warm,humid,low pressure and temperature rise weather,such as hybrid cyclone in which southly flow dominating.Overall,the greater probability of having high AI is connected with Anticyclonic Northerly（AN）and Anticyclonic Northwesterly（ANW）weather circulation situations,while low AI is connected with Cyclonic Southwesterly（CSW）situations.We considered the time lag of the weather types for the previous 7 days of the current day.The results showed thatthe highest AI for COPD occurring in all the age groups analysed was linked to N、W、and Northwesterly（NW）situations.These situations produce a type of a lower temperature and humidity,a higher wind speed and a drop in temperature.These cold and dry weather favours virus transmission and leads to weakened respiratory system defences.It was also found that the effects of Cyclonic Northerly（CN）and AN situations on the number of hospital admissions had a small time lag delayed by 2 days,while the effects of N、Northeasterly（NE）、W、A、Cyclonic Westerly（CW）、Anticyclonic Northwesterly（ANW）situations were delayed by 6days or longer.The greatest admissions were associated with CW situations 6 days earlier.The lowest admissions with the number of patients below the average was associated with Southerly（S）、SW and A situations that always resulted in a lower wind speed and a rise in temperature.There were totally 11 cold spells happened from 2009 to 2012 in Changchun,with maxima occurring in December and characterized by N situation.The mostly common circulations during the cold spell burst were directional atmospheric patterns and hybrid anticyclone in which northly flow dominate.The lag effect of the cold spell was obvious and consistent in all gender and age,the admission index（AI）reached the highest level four days after t he cold wave occurred.The high admission indices obtained in Changchun were usually associated with a drop in temperatures and relative humidity.