washing equipment. Dye transfer inhibitors prevent dyes from one article from coloring other items, these are generally polar water-soluble polymers such as polyvinylpyrrolidone, to which the dyes preferentially bind. Antiredeposition agents such as carboxymethyl cellulose are used to prevent fine soil particles from reattaching to the product being cleaned. Commercial or industrial laundries may make use of a laundry sour during the final rinse cycle to neutralise any remaining alkali surfactants and remove acid-sensitive stains. A number of ingredients affect aesthetic properties of the item to be cleaned or the detergent itself before or during use. These agents include optical brighteners, fabric softeners, and colorants. A variety of perfumes are also components of modern detergents, provided that they are compatible with the other components and do not affect the color of the cleaned item. The perfumes are typically a mixture of many compounds, common classes include terpene alcohols (citronellol, geraniol, linalool, nerol) and their esters (linalyl acetate), aromatic aldehydes (helional, hexyl cinnamaldehyde, lilial) and synthetic musks (galaxolide). Market Worldwide, while liquid and powdered detergents hold roughly equal market share in terms of value, powdered laundry detergent is more widely used. In 2018, sales of powdered detergent measured 14 million metric tons, double that of liquids. While liquid detergent is widely used in many Western countries, powdered detergent is popular in Africa, India, China, Latin America, and other emerging markets. Powders also hold significant market share in eastern Europe and in some western European countries due to their advantage over liquids in whitening clothes. According to Desmet Ballestra, designer and builder of chemical plants and detergent-making equipment, powdered detergents have a 30–35% market share in western Europe. According to Lubrizol, the powdered detergent market is growing by 2 percent annually. Environmental concerns Phosphates in detergent became an environmental concern in the 1950s and the subject of bans in later years. Phosphates make laundry cleaner but also cause eutrophication, particularly with poor wastewater treatment. A 2013 academic study of fragranced laundry products found "more than 25 VOCs emitted from dryer vents, with the highest concentrations of acetaldehyde, acetone, and ethanol. Seven of these VOCs are classified as hazardous air pollutants (HAPs) and two as carcinogenic HAPs (acetaldehyde and benzene)". The EEC Directive 73/404/EEC stipulates an average biodegradability of at least 90% for all types of surfactants used in detergents. The phosphate content of detergents is regulated in many countries, e.g., Austria, Germany,