Comparison of air pollution in Shanghai and Lanzhou based on wavelet transform

Abstract

For a long-period comparative analysis of air pollution in coastal and inland cities, we analyzed the continuous Morlet wavelet transform on the time series of a 5274-day air pollution index in Shanghai and Lanzhou during 15 years and studied the multi-scale variation characteristic, main cycle, and impact factor of the air pollution time series. The analysis showed that (1) air pollution in the two cities was nonstationary and nonlinear, had multiple timescales, and exhibited the characteristics of high in winter and spring and low in summer and autumn. (2) The monthly variation in air pollution in Shanghai was not significant, whereas the seasonal variation of air pollution in Lanzhou was obvious. (3) Air pollution in Shanghai showed an ascending tendency, whereas that in Lanzhou presented a descending tendency. Overall, air pollution in Lanzhou was higher than that in Shanghai, but the situation has reversed since 2015. (4) The primary cycles of air pollution in these two cities were close, but the secondary cycles were significantly different. The aforementioned differences were mainly due to the impact of topographical and meteorological factors in Lanzhou, the weather process and the surrounding environment in Shanghai. These conclusions have reference significance for Shanghai and Lanzhou to control air pollution. The multi-timescale variation and local features of the wavelet analysis method used in this study can be applied to varied aspects of air pollution analysis. The identification of cycle characteristics and the monitoring, forecasting, and controlling of air pollution can yield valuable reference.

Association of air pollution with outpatient visits for respiratory diseases of children in an ex-heavily polluted Northwestern city, China

“…PM 2.5 , particulate matter with aerodynamic diameter ≤ 2.5 μm; PM 10 , particulate matter with aerodynamic diameter ≤ 10 μm; NO 2 , nitrogen dioxide; SO 2 , sulfur dioxide outpatients were insignificant, which is not consistent with the findings from other studies [35,37]. Shanghai is characterized by a higher degree of urbanization and industrialization than Lanzhou, so the PM 10 of which mainly comes from traffic and industry pollution sources, similar to that in Yichang [36,38]. However, the PM 10 in Lanzhou was mainly contributed by raised dust containing higher level of crustal elements, which is not as poisonous as that in Shanghai and Yichang [39].…”

“…A study in Shanghai during 2013-2015 found that an interquartile range (IQR) increase in PM 2.5 , SO 2 and NO 2 was associated with a 8.81, 17.26 and 17.02% increase for daily pediatric respiratory emergency visits in lag 03, respectively [35], which is higher than our study. The possible explanation is that the air pollution level in Shanghai of 2013-2015 showed a trend of rising, but it has been persistently declining in Lanzhou since 2013 [36]. However, a study conducted in Yichang during 2014-2015, China, observed that each IQR increase in PM 2.5 and NO 2 concentrations corresponded to a 1.91 and 1.88% increase of pediatric respiratory outpatient visits at current day, respectively [37], which was higher for PM 2.5 but lower than our study for NO 2 .…”

“…Lanzhou is located in Northwestern China with a narrow and long valley basin and low winds, stable stratification especially inversion, which blocks the air streams and makes the pollutants difficult to disperse [53]. In addition, coal use in the winter also increases the level of air pollution [36]. These factors may lead the air pollution of Lanzhou to be the most severe in cold seasons.…”

Long-Term Changes in Premature Death of Lung Cancer in a Developed Region of China: A Population-Based Study From 1973 to 2019

“…A long-period comparative analysis of air pollution in Shanghai analyzed the continuous Morlet wavelet transform on the time series of a 5274-day air pollution index from 2000. The monthly variation in air pollution in Shanghai was not signi cant, Air pollution in Shanghai showed an ascending tendency, but the situation has reversed since 2015 [19]. It can be seen that in the past 50 years, especially before 2015, air pollution in PNA has led to an increase trends in years of life lost due to premature death in people with lung cancer in Shanghai.…”

Development of Modern Standards for Energy Efficiency of Industrial Enterprises Within the European Union Policy

“…In order to prevent local emissions due to energy savings, an indicator of local air pollution is determined. Based on a typical break-down of energy savings by energy source, local pollutants, which come mostly from local sources, such as transport or industry, using end-use and fuel specific emission factors are avoided (Su et al, 2019). Avoided emissions of air pollutants are calculated by multiplying energy savings expressed in primary terms by the average emission factor of the country, for each type of pollutant, per unit of final energy consumed (Sun et al, 2019).…”