Exposure to wildfire smoke may increase lung cancer patients' risk of dying from their disease, particularly among non-smokers, but the effect may be mitigated by certain cancer treatments, according to a large California study presented at a major medical meeting on Saturday.

The US State Department on Friday ordered all US embassies and consulates to “immediately begin additional vetting” for anyone seeking a visa to travel to Harvard University “for any purpose.”

The vetting will go beyond student applicants and includes faculty, employees, contractors, guest speakers and tourists, according to the cable seen by NBC News.