claim: urban air pollution may decrease covid-19 case-fatality and mortality rates in the united states
evidence_1: discussions and conclusions long-term exposure to no2, which largely arises from urban combustion sources such as traffic, may enhance susceptibility to severe covid-19 outcomes, independent of longterm pm2.5 and o3 exposure.", "while the risk factors of covid-19 are still under investigation, environmental factors, such as urban air pollution, may play an important role in increasing population susceptibility to covid-19 pathogenesis.", "moreover, continuation of current efforts to lower traffic emissions and ambient air pollution levels may be an important component of reducing population-level risk of covid-19 deaths.", 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  "the results support targeted public health actions to protect residents from covid-19 in heavily polluted regions with historically high no2 levels.")