Associations between air pollution, climate factors and
outpatient visits for eczema in West China Hospital,
Chengdu, south-western China: a time series analysis
Department of Dermatology, West China School of Medicine, Sichuan University, Chengdu, Sichuan, China
Department of Medical Statistics, West China School of Public Health, Sichuan University, Chengdu, Sichuan, China
Department of Dermatology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
*Correspondence: L. Li. E-mail: firstname.lastname@example.org
Background Eczema is one of the most common inﬂammatory dermatoses that can be provoked as a result of exter-
nal and internal factors. With dense population and rapid economic development of China, air pollution is still a serious
problem and the prevalence of eczema has been elevating.
Objective To determine the association and lagged effects between environmental factors and the outpatient visits for
Methods Data of daily outpatient visits for eczema at the clinics of dermatology in West China Hospital within the last
5 years were collected. Data of environmental factors of Chengdu during the same period, including temperature, rela-
tive humidity, barometric pressure, wind speed and air pollutants concentrations like sulphur dioxide (SO
) and particular matter (PM
), were gathered. The distributed lag nonlinear model was used to statistically
examine the relationship between eczema and environmental factors and their lagged effects.
Results Correlation analysis showed that eczema outpatient visits were positively correlated with the air pollutants and
were negatively correlated with relative humidity. The barometric pressure and wind speed inﬂuenced the outpatient vis-
its in association with air pollutants.
Conclusion This study provides evidence that environmental factors like relative humidity and multiple air pollutants
inﬂuence the incidence and prevalence of eczema and have lagged effects.
Received: 18 June 2017; Accepted: 15 November 2017
Conﬂicts of interest
The authors declare no conﬂict of interests pertinent to this study. There are no conﬂict of interests to be
Eczema is one of the most common inﬂammatory dermatoses
characterized by erythema, scales, vesicles, crusts, pruritus and a
chronic course of exacerbations and remissions. Its high preva-
lence puts a considerable burden on both eczema sufferers and
society and negatively impacts the quality of life for a large num-
ber of individuals.
Several studies documented that the preva-
lence of eczema has increased rapidly worldwide in the past
20 years, and a signiﬁcant growing number of eczema patients
imply eczema is becoming a major public health problem given
the huge population of China.
Eczema is usually caused by allergic contact dermatitis, atopic
dermatitis and irritant contact dermatitis. Some studies have
shown that lots of internal and external factors provoked
eczematous lesions, including genetic predisposition, stress,
infections, food intake, inhalant allergens and other daily
A growing body of literature supported that the envi-
ronmental factors such as temperature, relative humidity, wind
speed and air pollutants may play important roles in the exacer-
bation of eczematous rashes.
Several studies suggested that sea-
sonal climate changes might lead to the seasonal variation of
prevalence and clinical features in eczema.
A study in Shang-
hai provided evidence that high temperature and low relative
humidity could increase the incidence of eczema.
However, recent studies have not adequate evidence for the
association between eczema and environmental factors while our
© 2017 European Academy of Dermatology and Venereology
2018, 32, 486–494