AIR chất gây ô nhiễm các chất ô nhiễm không khí rơi vào hai loại chính: (1) những người được phổ biến trên toàn khu vực bởi vì họ là những sản phẩm của các hoạt động như giao thông, không gian, điện và sưởi ấm nước, và tiêu huỷ chất thải sinh hoạt, (2) những ngườitạo ra bởi các hoạt động như hóa chất, sản xuất và chế biến nông sản có chất gây ô nhiễm các sản phẩm phụ có xu hướng được bản địa hoá tại các khu vực gần đó hoặc được lan truyền khoảng cách. | AIR POLLUTANT EFFECTS AIR POLLUTANTS Air pollutants fall into two main categories 1 those that are pervasive throughout areas because they are the products of daily-life activities such as transportation power generation space and water heating and waste incineration and 2 those generated by activities such as chemical manufacturing and agricultural processing whose pollutant byproducts tend to be localized in nearby areas or are spread long distances by tall stacks and prevailing winds. Air pollutants are also categorized by their emission characteristics 1 point sources such as power plants incinerators and large processing plants 2 area sources such as space and water heating in buildings and 3 mobile sources mainly cars and trucks but also lawn mowers and blowers and airplanes. The United States has established National Ambient Air Quality Standards NAAQS for seven pollutants that are pervasive and are threats to public health and welfare. The Clean Air Act which initiated this program was passed in 1963 and last amended in 1990. The primary standards are intended to protect health and the secondary standards protect public-welfare interests such as visibility and danger to animals crops and buildings. The standards reflect for the most part but not always a conservative approach in favor of the protection of health. It is notable that the public who in the final analysis must pay the cost appears to be firmly committed to enforcement of the standards without overwhelming concern for costs. The act requires the states to determine the status of their air quality and to find and introduce the controls that will enable them to meet these standards. Their proposal describing how and when the standards will be met is submitted to the EPA . Environmental Protection Agency as an implementation plan for approval. Meeting target dates for air-quality standards has been problematic because the complex system that has to be managed includes important socioeconomic and
