U.S. discussion on air pollution raises questions for Canada.
D000397:Air Pollution / Q000517:prevention & control*; D000787:Angina Pectoris / Q000097:blood; D002170:Canada; D002248:Carbon Monoxide / Q000097:blood; D002263:Carboxyhemoglobin; D006076:Government; D007878:Legislation as Topic; D008027:Light; D010126:Ozone; D014481:United States; D014505:Urban Population
D010126:Ozone; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin