Beijing Metropolitan Area Research Articles

Vertical distribution of ozone in the planetary boundary layer at the Ming Tombs, Beijing

Surface ozone (O 3 ) and vertical O 3 distribution in the planetary boundary layer (PBL) at the Ming Tombs (40°17′15″N, 116°12′51″E), Beijing during September 7―12, 2001 were measured by ground based measurements and an in-situ tethersonde system. The results indicated that O 3 concentration measured at surface level agreed well with that measured by tethersonde system in daytime when active thermal mixing was dominated. Ozone showed the lowest concentration before the sunrise and then gradually increased in the morning and reached the maximum in the afternoon 14:00―17:00 (lst). After sunset, O 3 gradually decreased and resulted in low value below 200―300 m due to surface loss processes and chemical destruction in stable boundary layer characterized by temperature inversions. High O 3 was observed whenever there was pollutants transport from the metropolitan areas of Beijing. Our analysis suggested the complex terrain of the Ming Tombs region caused pollutants transported from Beijing to accumulate in the PBL, and resulted in severe O 3 pollution, with a maximum over 160×10 -9 , when the synoptic conditions was favorable for photochemical O 3 production.

Comparative analysis of patients with clinically diagnosed colorectal cancer and those detected by mass screening

To analyze the differences and similarities between patients with colorectal cancer (CRC) who had been clinically diagnosed (CD) and those detected by mass screening (MS), and thus clarify the practical significance of CRC screening in China. All the data for the CRC patients in the CD group were collected by registration through a cohort study, and the patients in the MS group were selected from mass screening of a natural population of 19 852 in Beijing Metropolitan area. CRC was confirmed pathologically in both groups. Patients over the age of 50 years with CRC comprised 81.9% of the CD group and 83.3% of the MS group; the percentage of Dukes A + B was 41.1% and 91.7%, respectively; 0.28% of individuals with risk factors in the MS group were found to have CRC, whereas 0.05% did not (P < 0.05). Endoscopically, 44.7% of the protruding type CRC were Dukes A or B compared with only 10% of the ulcerated type (chi(2) = 22.304, P < 0.001). The positivity rate of the fecal occult blood (FOB) test was 79.9% in Dukes A + B and 82.0% in Dukes C + D, showing no difference between the FOB test and Dukes staging in diagnosing CRC (chi(2) = 0.087, P = 0.768). The percentage of patients with increased serum concentration of carcinoembryonic antigen in Dukes C + D was significantly higher than that in Dukes A + B (chi(2) = 5.547, P = 0.019). Among the moderately and well-differentiated CRC, 51.8% (159/307) were Dukes A + B, resulting in a significant difference (chi(2) = 14.504, P < 0.001). There was a familial history of malignancies in 17.9% of CRC cases and 14.6% of their first-degree relatives suffered from malignant tumors. The incidence of CRC in Beijing Metropolitan area has been rising significantly. The staging and prognosis of CRC involves symptomatology, laboratory tests, endoscopic findings and pathologic characteristics. Mass screening is effective for detecting early CRC in China.

Risk factors for epithelial ovarian cancer in Beijing, China.

A study in Beijing, China of 112 pathologically confirmed epithelial ovarian cancer cases and 224 age-matched community controls enabled evaluation of risk in relation to reproductive, medical, familial, and selected lifestyle factors. An inverse relationship was observed between the number of full-term pregnancies and ovarian cancer risk. Compared to nulliparous women, subjects with one, two, or three full-term pregnancies were at 50%, 70%, or 90% reduced risks, respectively (P for trend less than 0.01). A positive correlation was found between the number of ovulatory years and risk, with a 2.6-fold increased risk for women with 30 or more compared to less than 10 ovulatory years (P for trend less than 0.01). Infertility, as estimated in various ways, was also found to be an important risk factor. When parity was taken into account, age at first pregnancy was not related to ovarian cancer risk. No protective effect was associated with mumps virus infection. In contrast, risk increased significantly as serum mumps virus antibody titres increased (P for trend less than 0.01). An elevated risk was found in women with a history of long-term (greater than 3 months) application of talc-containing dusting powder to the lower abdomen and perineum (Relative risk 3.9, 95% confidence interval: 0.9-10.63). These findings suggest that Chinese women have risk factors similar to those of occidental women.

THE BEIJING AUDIENCE STUDY

Communication research in China is in an early stage of development, but there are an increasing number of training and research activities in universities and in independent institutes. The Beijing Audience Survey in 1982 was the first large-scale communication field study in China. It showed a very high degree of penetration of the mass media among both urban and rural audiences in the metropolitan area of Beijing, with 97% of the sample of 2430 individuals listening daily to radio, 92% viewing television, and 81% reading a daily newspaper. The high degree of exposure to television is surprising, given that the purchase of TV receivers by Chinese families only began at the end of the Cultural Revolution in 1976.