How is air quality measured?

As smoky air from Canada’s wildfires shrouds broad swaths of the U.S., here are seven facts you should know about measuring air quality.

Lab-grown chicken approved for sale in U.S.

For the first time, U.S. regulators on Wednesday approved the sale of chicken made from animal cells, allowing two California companies to offer “lab-grown” meat to the nation's restaurant tables and eventually, supermarket shelves.