INDEX VALUE* PSI DESCRIPTOR GENERAL HEALTH EFFECTS CAUTIONARY STATEMENTS RESPONSE PLAN for 24-hour psi Up to 50 Good None for the general population. None required. 51 to 100 Moderate Few or none for the general population. None required. 101 to 200 Unhealthful Mild aggravation of symptoms among susceptible people, with irritation symptoms in the healthy population. Persons with existing heart or respiratory ailments should reduce physical exertion and outdoor activity. General population should reduce vigorous outdoor activity. ENV will continue to inform the public on PSI and health advisories. Outdoors physical education lessons, sports and games to be cancelled. 201 to 300 Very unhealthful Significant aggravation of symptoms and decreased tolerance in persons with heart or lung disease; widespread symptoms in healthy population. Elderly and persons with existing heart or lung disease should stay indoors and reduce physical activity. General population should avoid vigorous outdoor activity. Fuel-burning industries and vehicle fleet owners to cut down emissions.
301 to 400 Hazardous Early onset of certain diseases in addition to significant aggravation of symptoms and decreased exercise tolerance in healthy persons. Elderly, children and persons with existing diseases should stay indoors and avoid physical exertion. General population should avoid unnecessary outdoor activity. MOE and Sports Council to consider closing schools and sports complexes. Over 400 Hazardous PSI levels above 400 may be life-threatening to ill and elderly persons. Healthy people experience adverse symptoms that affect normal activity. All persons should remain indoors, keeping windows and doors closed, and minimise physical exertion. Civil Defence sirens will be sounded and the public will have to tune in to radio for announcements on air quality and health advisories. The public will be forewarned of additional measures to be taken.
* The index value refers to the 24-hour Pollutant Standards Index (PSI) value and not to the 3-hour PSI value.
Only the 24-hour PSI is correlated to the health effects outlined in this
table.
Done by Amndeep Pannu and Rhiannon Deroux