The Beijing Municipal Heavy Air Pollution Emergency Response Program includes a four-tier color alert system.
A Red alert, the highest, will be issued for heavy pollution that is expected to last more than 3-days.
An air quality index of over 200 will be defined as "heavy pollution".
Orange and red alerts are to be issued 24-hours before heavy pollution days to give people in Beijing advanced warning.
Sun Feng with the Beijing Municipal Environmental Monitoring Center says issuing alerts before heavy pollution days should help authorities deal with air pollution.
"If we try to control air pollution before it happens, the accumulation of pollutants may be reduced. Accordingly, a
