Air pollution

Air pollution is considered by many as the main environmental problem. It is undetectable by the naked eye in contrast to other pollutions such as noise, solid waste, sewage and more. Due to general population being unaware of air pollution, some think that it is less problematic then “noticed” environmental topics. Nonetheless, air pollution is a serious problem which causes numerous environmental and health damages.

The source of air pollution can be divided to two main sectors:

  1. Air pollution from the industry.
  2. Air pollution from the exhaust of vehicles.
 

Air pollution from the industry:

 

Numerous factories such as chemicals factories, quarries, concrete factories, and more have an emission full of polluters. The range of polluters is enormous and includes organic solvents, pesticides, respiratory particles and etc. which can be a health hazard if higher then the threshold (determined by toxic and epidemiology research). These health damages include short range effects (such as respiratory problems or a stinging in the eyes) due to exposure to high concentration of polluters and long range effects which can cause a rise in the morbidity of chronic diseases and cancer. These thresholds are determined in two main documents. One is the regulations for hazards prevention - air pollution 1992, the other is the Almog committee report which deals with the definition of thresholds for air polluters. The regulations are about specific common polluters such as nitrogen oxide, particles and sulfur dioxide. Being within these thresholds is a requirement of the authorities. The Almog committee lists many polluters that are used in the industry and their thresholds are used as a primary threshold which is the base for the wanted thresholds. These days, regulations for air pollution are updated by the Environmental Protection ministry as part of the “clean air act”.

To determine the potential affect of industry on its environment, the emission is estimated based upon known measurements from similar facilities, engineering equations, computer stimulations and/or measurements from the specific factory (if exists). Due to the uncertainty of these methods, usually a few methods are applied at parallel and the emission determined is based on their combination. The dispersing of air polluters is the next stage and it is estimated by analytic or numeric models. The main input is the emission intensity determined at the previous stage. In addition, the metrological conditions (wind direction, strength and more) and the local topography are two major inputs for the models. Wrong parameters for these inputs will lead to wrong estimations of the effect of the factory on its environment and can cause environmental hazards. The air polluters concentration estimated by the dispersion model is compared to the relevant threshold values. If the estimated values are higher then the threshold the factory is required to take steps to improve the air quality around it such as changing the raw materials used (using natural gas as fuel instead of fuel oil), changing work procedures, change the method of emission (such as installing chimneys) and installing treatment facilities. The improvement of air quality is a process which requires an integration of different environmental aspects such as energetic efficiency, toxic waste, sewage and more. Therefore, other then reduction of the emission source (by reducing amounts or altering raw materials) each solution is a compromise between different environmental aspects and needs to be thoroughly examined so as not to solve one environmental problem while causing another environmental problem elsewhere (for example absorption of toxic gasses and thus causing toxic sewage). 

 

Air pollution from vehicles

Exhaust of vehicles consists of an additional source of air pollution. While the materials which are emitted from the industry are numerous, the vehicles emit mainly nitrogen oxide, CO2, particles and hydrocarbons. A secondary polluter, ozone, is created by reactions of the materials emitted from the vehicles. The intensity of polluters at different road segments depends on traffic volume, types of vehicles driving and topological conditions of the road. The pollution from vehicles at road segments with a positive incline, in which the engine works at a high capacity, is usually considerably elevated compared to roads with a negative incline. This pollution intensity is the input of dispersion models, similar to estimations of industry dispersion. Recently vehicles are technologically improved to reduce pollution emitted. In addition, the public is encouraged to buy these vehicles by lower tax and public transportation is improved. These steps are taken to maintain reasonable air quality at center of towns and around inter-city roads despite the rising usage of transportation.