Atmospheric particulate matter (PM) is a complex mixture of elemental and organic carbon, ammonium, nitrate, sulphate, mineral dust, trace elements, and water . PM, esp. PM10 (particulate matter with an aerodynamic diameter smaller than
Since the year 1999, NO2 and PM10 have been reported in Environmental Bulletin in place of NOx and TSP in major cities like Beijing of China . Urban residents have been demanding to improve air quality as the Chinese Government has established air quality monitoring sites in nearly every city, providing the public with detailed information regarding air condition and daily air pollution index (API). Residents express more concerns about air quality in their cities .
Air pollution index (API) data have been extensively used in studies on air pollution in China  , based on a network of multiple monitoring stations, which represent different zones (industrial, commercial, traffic and residential) and the suburban background. Five designated pollutants: PM10, SO2, NO2, CO and O3 (in some cities three pollutants were collected: PM10, SO2 and NO2) are measured .
API is a simplified figure that joins the several kinds of air pollutant concentration by conventional monitoring into a single concept numerical form, and hierarchically represents air quality status and the degree of air pollution. The result of the index (API) can directly conveniently describe the air quality in a city within a designated period of time. Calculating API sub-index (sub-API) of each pollutant, the biggest sub-API of all kinds of pollutants in the pollution is the city’s air pollution index of the day (API), and the corresponding pollutant with the biggest sub-API is identified as the principal pollutant for the city . That is to say, every day air pollution index API of city represents the primary pollutant of that day.
In 2003, as the primary pollutant in
More reports are based on atmospheric particulates to study the respiratory system and cardiovascular system diseases  , but the relationship research between air pollution index (API) and related disease was less than rare. In order to further discuss the air pollution characters and potential hazard in
2. Material and Methods
The API of 2005 and the data of NO2, SO2 and PM10 of 2006
3. Result and Analysis
3.1 Mutual Relations among NO2, SO2 and PM
Between January 9, 2006 and October 3, 2009, the data of NO2, SO2 and PM10 of 361 days were collected from 9 atmospheric monitoring spots of Nanchang city. The average values of NO2, SO2 and PM10 were 19.70 ± 8.56 µg/m3, 44.60 ± 10.45 µg/m3, 62.30 ± 19.76 µg/m3 (see Table 1), which were far lower than the concentrations of air pollution of Jinan city of China, NO2 42.1 ± 25.8 µg/m3, SO2 59.9 ± 61.7 µg/m3, PM10 140.6 ± 71.6 µg/m3, respectively ; there were relations among them (see Table 2). The above results indicate that the API constitutes the primary daily pollutant of the city and can well reflect the local air pollution condition of
3.2. Effect on Hospital Visits of Cardiovascular Disease from API
From January 1 to December 31 in 2005, the daily hospital visits of cardiovascular disease were 67 - 317 cases,
Table 1. Air quality monitoring results of 2006-2009 in Nanchang city (unit: µg/m3).
the mean of which was 144.92 ± 37.91 cases. API’s influence on the hospital visits of cardiovascular disease and its correlation were shown in Figure 1, F = 6.174, R2 = 0.0168, R = 0.13, P = 0.013 < 0.05, the relationship between API and hospital visits of cardiovascular disease was closely related (positive correlation). These results are similar to those observed in other studies  , which showed the effect of ambient air pollution on hospital admissions of circulatory system diseases and daily cardiovascular mortality.
3.3. Effect on Hospital Visits of Respiratory Disease from API
Between January 1, 2005 and December 31, 2005, the daily hospital visits of respiratory disease were 0 - 279 cases, and the mean was 77.02 ± 38.21 cases. API’s influence on the hospital visits of respiratory disease and its correlation showed in Figure 2, F = 4.247, R2 = 0.0116, R = 0.11, P = 0.040 < 0.05, API was closely related to hospital visits of respiratory disease (positive correlation), which was consistent to the research result of Wang Yan , showing the effect of air pollution on the daily hospital visits of respiratory disease.
Table 2. Relationship among NO2, SO2, PM10.
Figure 1. Relationship between API and hospital visits for cardiovascular diseases.
Figure 2. Relationship between API and hospital visits for respiratory diseases.
3.4. Effect on Hospital Visits of Ophthalmology Disease from API
Between January 1, 2005 and December 31, 2005, the daily hospital visits of ophthalmology disease were 10 - 282 cases, the mean was 124.38 ± 51.20 cases. API’s influence on the hospital visits of ophthalmology disease and its correlation showed in Figure 3, F = 5.145, R2 = 0.0141, R = 0.12, P = 0.024 < 0.05, API was positively correlated to hospital visits of ophthalmology disease.
3.5. Effect on Hospital Visits of ENT Disease from API
Between January 1, 2005 and December 31, 2005, the daily hospital visits of ENT disease were 13 - 343 cases, and the mean was 169.15 ± 67.10 cases. API’s influence on the hospital visits of ENT disease and its correlation was shown in Figure 4, F = 4.362, R2 = 0.0121, R = 0.11, P = 0.037 < 0.05, API was positively correlated to hospital visits of ENT (ear-nose-throat) disease.
3.6. Effect on Hospital Visits of Dermatology Disease from API
Between January 1, 2005 and December 31, 2005, the daily hospital visits of dermatology disease were 0 - 202 cases, and the mean was 99.94 ± 40.15 cases. API’s influence on the hospital visits of dermatology disease and its correlation was shown in Figure 5, F = 2.055, R2 = 0.0058, R = 0.076, P = 0.153 > 0.05, and the relationship between API and the hospital visits of dermatology disease was not evident.
Figure 3. Relationship between API and hospital visits for ophthalmology diseases.
Figure 4. Relationship between API and hospital visits for otorhinolaryngology diseases.
Figure 5. Relationship between API and hospital visits for dermatology diseases.
The average concentrations of NO2, SO2, PM10 from 2006-2009 were 19.70 ± 8.56 µg/m3, 44.60 ± 10.45 µg/m3, 62.30 ± 19.76 µg/m3. There were closely relations among NO2, SO2 and PM10. The urban air pollution index (API) with daily primary pollutants as the foundation can well reflect the local air pollution condition.
The API of Nanchang city is closely related to the daily hospital visits of cardiovascular diseases, respiratory diseases, eye diseases and ENT diseases (positive correlation), but not related to the hospital visits of dermatology disease. The above research about the relationship between API and hospital visits of related diseases, such as cardiovascular diseases, respiratory diseases, eye diseases, ENT diseases and dermatology diseases, has not been reported before, so further in-depth study esp. about Pb pollution of PM2.5 in the industry area and traffic lines will be necessary.
This study was supported by Jiangxi Provincial Health Bureau of P. R. China grant NO: 20122018, and Nanchang City Scientific Technology Bureau of P. R. China grant NO: 2014-CXYHZ-ZYHJ-001 (Area distribution characteristics of PM2.5 pollution and its related influencing factors analysis and the prevention & control measures in Nanchang City), and Jiangxi Provincial Research Center of Industry Safety Engineering Technology of P. R. China grant NO: 2013GGY003.
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