Clear skies not so clean.
D000393:Air Pollutants / Q000009:adverse effects*; D004777:Environment; D004781:Environmental Exposure; D006801:Humans; D008175:Lung Neoplasms / Q000209:etiology*; D011050:Policy Making; D011057:Politics; D001335:Vehicle Emissions / Q000009:adverse effects*
D000393:Air Pollutants; D001335:Vehicle Emissions