Filter demand in developed parts of the world is expected to expand as well. Product sales will be stimulated by largely favorable economic climates and higher per-capita income levels, resulting in increased manufacturing output and consumer spending, which will boost related filter demand, according to Freedonia. The implementation of stricter environmental standards, like those for diesel engine particulate emissions, will also contribute to market gains in these areas. However, new housing starts are expected to decline in the United States and Japan, and population levels will remain flat or edge down in some European nations, limiting increases in associated filtration product demand. Air purification filters will record the strongest sales advances through 2011, spurred by growing manufacturing and mining output, rising urban population levels, and the construction of numerous new power plants and waste incinerators, leading to a deterioration in average air quality and the enactment of tougher air pollution control laws and regulations. Growing concerns about indoor air quality will also drive demand for home air filtration products. Fluid filters will register the next strongest gains, stimulated by increases in nonagricultural water withdrawals; an ongoing trend toward urbanization, resulting in greater spending for water and wastewater treatment; and the implementation of more stringent water pollution control standards. Internal combustion engines and related filters will remain the largest product segment in value terms, according to Freedonia. Transportation equipment is by far the largest market for filtration products, but it is also the slowest growing. Demand for filters in the manufacturing and utility markets will expand at faster rates through 2011, benefiting from healthy increases in manufacturing output and the construction of numerous electric and water utility facilities around the world.