text: For example , adjusting for age differences between subjects in the economic studies and those affected by air pollution may imply the need to adjust the $ 6 million VSL downward , but the involuntary nature of air pollution-related risks and the lower level of risk-aversion of the manual laborers in the labor market studies may imply the need for upward adjustments .
  
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  Pollution related risks are fixed and unchanging in relation to age .