Effects Of Air Mixed Pollutants On The Microecology In Respiratory Tract Of Rats

Air pollution is the environmental problem with the development of science and civilization as well as the speeding up of industrialization, generated because of the dense urban population, and rapid increase of fossil energy and fuel combustion. The sources of air pollutants in the city are similar, mainly composed of particle pollutants and gaseous pollutants. According to the aerodynamics diameter, particulates may be divided into: total suspended particulates and inhalable particulates, of which the latter may be divided into coarse particulates (PM2.5~10) and fine particulates (PM2.5). PM2.5 is mainly originated from combustion of fossil fuel. With small grain diameter, large quantity and surface area, slow settlement speed, far dissemination distance, PM2.5 may provide carriers for chemicals, bacteria and viruses. PM settling in human body is primarily PM2.5. Due to different regions and sources of pollution, chemical compositions of PM2.5 are greatly different. Major components include sulfate, nitrate, ammonium, carbon particles, metal particles, minerals, and organic compounds adsorbed by them. Breathing is one of the main routes by which suspended particulates and other harmful substances in the air enter into human body, and respiratory system is the direct target organ that air pollutants exert effect on. The number of residents who suffer from pharyngeal irritation and much sputum increases in areas with heavy air pollution compared with areas having light pollution, and the body's immune function may be damaged by repetitive long-term irritation of environmental pollutants with low concentration.At present, domestic and foreign research on air pollution is only restricted in aspects such as health investigation, dangerous factor analysis and pollution governance. In the earlier research, we have simulated the atmospheric pollutant mixture, established the animal model of air pollution, and discussed the effect of air pollution on the micro ecology of respiratory tract: air pollution (PM10) may cause unbalance of micro ecology in organisms, exert toxic and harmful effect on the normal bacteria colony in the oropharynx of upper respiratory tract in rats, resulting in the change of micro environment. The content of normal bacteria colony reduced, the pathogenic bacteria and the conditioned pathogen colonized to facilitate the occurrence of diseases in the respiratory tract. Air pollution may lead to increased bacteria density in the oropharynx of rats, increased pathogen number and the change of bacteria number, and the change of micro ecology in respiratory tract may be taken as the sensitive indicator of harm by air pollution to organisms. In the further research, we mainly discussed the effect of fine particulates of atmospheric pollutant mixture on the micro ecology of respiratory tract. we mainly gathered smaller inspirable particles (PM 2.5), and used 78 Wistar rats in the experiment, divided into 6 groups: 3 experimental groups (1d, 7d, 30d) and 3 control groups (1d, 7d, 30d). Polluted dusts were poured into the trachea of rats one time in the non-exposed manner under the ether anesthesia. Materials were taken from the oropharynx of rats with pharynx swab before it was contaminated by polluted dusts. In experimental rats, 1ml 10mg/PM2.5 normal saline was injected, and in control rats 1ml normal saline was injected. Air mixture with SO2 and NO2 and CO was inhaled dynamically by the experimental group, and normal air inhaled by the control group. The similarities and differences before and after the oropharynx of rats was contaminated by polluted dusts were studied, the ultra-structure of the trachea and pulmonary tissue of rats before and after contamination by polluted dusts was observed with the transmission electron microscopeAfter contamination by polluted dusts, detected ratios of most bacteria increased significantly (p< 0.05), the total quantity of aerobes and anaerobes increased, and colony density also increased, and the change is significant (P< 0.01). Partial bacteria appeared after contamination. The colony density of aerobes increased remarkably 1 day after contamination by polluted dusts, significantly higher than the control group (P< 0.05), reduced obviously 7 days after contamination, and obviously increased 30 days after contamination (P< 0.05). With the prolonging of contamination time, it showed compensation state with obvious trend of fluctuation. The comparison between groups of different contamination time also showed the same change trend in terms of total quantity of bacteria, with significance (P< 0.05), but there was no significant difference in anaerobe. Contamination by polluted dusts caused inflammatory damage to the trachea and pulmonary alveolus of rats, which aggravated with the prolonging of contamination.The conclusion may be drawn that fine particulates of air pollutants may cause increased pathogenic bacteria in the oropharynx of rats, simultaneously the change of micro ecology results in the damage of pulmonary tissue and tracheal epidermis on the basis of pollution of fine particulates, therefore, fine particulates may change the micro ecology of respiratory tract and pose risk to organisms.