Air pollution in large cities

Probably the first instances of wider practical commercial use of fuel cell power plants will be in connection with heavier transport equipment used within cities and near cities buses and trucks supplying merchandise to the local trade and materials to construction sites. This heavy transport equipment is responsible for large part of the air pollution in large cities. They can be much more readily equipped with compressed hydrogen tanks. Creating an infrastructure for the distribution of and refueling with hydrogen is much easier within a city than all over the country. 

Motor vehicles are responsible for much of the air pollution in large towns and cities. They produce four particularly harmful pollutants ... 

Air pollution in large tropacal city with high traffic density results of measurements in Lagos, Nigeria. Sci. Total Environ. 169 25-31. 

A type of smog known as photochemical smog frequently occurs in large cities in simny, dry climates. When the pollutants from automobile exhaust enter the air and are exposed to sunlight, they interact to produce photochemical smog. This type of smog is generally worse on hot days and between 11 a.m. and 4 p.m. when exhaust has accumulated in the air. 

Atmospheric pollution resulting from the release of various harmful gases and solid particulates has the result that the air in large cities has become unsuitable and even dangerous for human life. For example, in some cities of Japan and Germany, policemen on the streets breathe oxygen from special cylinders. This opportunity also exists for pedestrians for a fee. In the streets of Tokyo and some other cities in Japan, oxygen cylinders are provided for children so that they can get fresh air on their way to school. Japanese businessmen have opened special bars where humans can get non-alcoholic drinks and fresh air. It should be noted that in the last few years, conditions have improved considerably. 

Air pollution, especially nitrogen oxides (NOx) contamination from the combustion of hydrocarbons, is a particularly serious problem in urban areas. Despite serious efforts toward emission control, the concentrations of NO often exceed the air-quality standard, especially in large cities. Ti02 photocatalysis appears to be a promising technology for the removal of low concentrations of NO from ambient air [79]. Daikin Industries has demonstrated the efficient removal of NOx from indoor air using a photocatalyst coated on activated carbon [25]. According to their results, the indoor NOx concentration decreases from 0.1 ppm to 0.06 ppm (the air-pollution standard) in 25 minutes. 

Beginning in the mid-1980s, published work on membrane fuel cells increased rapidly. This was driven by several factors, one of which was air pollution caused by the rising automobile population in large cities worldwide. This situation induced legislation in some places, such as in California, that required the introduction of a certain number of zero-pollution vehicles. Major carmakers worldwide began serious efforts to develop different versions of electric cars and associated power plants based on storage batteries and fuel cells. 

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