tailieunhanh - AIR POLLUTION MONITORING

As a consequence of the uncertainties in this global assessment, its quan- titative results cannot be confidently extrapolated to smaller geographic areas, such as specific countries or cities. The methods for estimation of exposure and extrapolation of concentration-response functions were devel- oped specifically for estimating burdens for large geographic regions, often in the absence of essential data on exposure and response. Where better data exist, as they currently do in some parts of the world, they should of course be used. Future estimates of the global burden of disease due to outdoor air pollution would benefit from both additional research and methods development. There is a critical need for better. | AIR POLLUTION MONITORING Air pollution from both stationary . factories and mobile . cars sources includes many substances such as carbon monoxide or lead which are harmful in themselves primary pollutants and other substances which react with other chemicals to form new harmful substances secondary pollutants . sulfur dioxide reacting with water and air to produce the sulfuric acid of acid rain . Primary pollutants Primary pollutants monitored in New Zealand particulates smoke dust and haze sulfur dioxide carbon monoxide the oxides of nitrogen benzene hydrogen sulfide and fluorides. Secondary pollutants Secondary pollutants are monitored in New Zealand ozone photochemical smog and acid rain. None of these currently are found in high enough concentrations to be a significant concern. Monitoring Pollutants Air pollution monitoring is done by a number of organisations in New Zealand including the Institute of Environmental Science and Research ESR the National Institute for Water and Atmosphere NIWA Regional Councils and industry. These pollutants are monitored through a variety of manual and instrumental methods with instrumental methods progressively replacing the manual ones. Manual sampling Manual methods include passive samplers in which solid matter is collected from the air flow by a filter paper tape samplers where pollutants are collected or react with a coating on a paper tape which is advanced at regular time intervals and bubblers which involve gases being bubbled through solutions in which particular pollutants undergo a reaction . The particular pollutants for which these methods can be used are outlined in Table 2. Instrumental methods Most of the instruments used are based on absorption or emission spectroscopic methods non-dispersive infra-red NDIR chemiluminescence flame photometry and fluorescence. In the case of airborne particles instruments have been developed on the basis of light scattering absorption of low-energy beta radiation and