Visibility impairment

{
  "id": "MLC-T-ENV-029779",
  "term": "Visibility impairment",
  "field": "Environment",
  "term_source": "Visibility Impairment",
  "definition": "1. Any humanly perceptible change in visibility (light extinction, visual range, contrast, coloration) from that which would have existed under natural conditions.\n\n2. Any humanly perceptible difference due to air pollution from anthropogenic sources between actual visibility and natural visibility on one or more days. Because natural visibility can only be estimated or inferred, visibility impairment also is estimated or inferred rather than directly measured.",
  "subject": "Outcomes",
  "references": [
    "40 CFR 51.301 (CFR 2013)",
    "40 CFR 51.301 (CFR 2017)"
  ],
  "url": "https://mlchart.com/terminology/environment/visibility-impairment/"
}