The ash warning level for aviation remained at orange, the second - highest level on a five - color scale, after several brief hikes to the top red in recent weeks. (scientificamerican.com)
If the consequences are mild, such as receiving an official warning level, you could likely handle it yourself. (zaviehlaw.com)
On 27 April, with 900 cases of suspected swine flu reported in Mexico, the World Health Organization (WHO) upgrades the pandemic warning level from 3 to 4 on a six - point scale. (newscientist.com)