Why is air pollution of concern?

Pollutants in the ambient air can affect general health and have an impact on physical performance, especially for physical activities involving prolonged exposure to polluted air or shorter term activities that are strenuous in nature. Such pollutants range from discharge and by-products of industrial origin, to particulate matter such as dust, smoke and soot. Recent regional concerns over land-clearing practices related to agriculture arose over the level of particulate matter in the air. Pollution affects indoor activities when polluted outdoor air enters indoor venues over a period of time.

 

What is the effect of air pollutants on the body?

The body’s reaction to polluted air is dependent on a few factors:

(1) The effect of polluted air depends on the level of the pollution, the time a person is exposed to the air, the temperature & humidity of the air, and the airway route the air enters the body. For example, in activities that require higher levels of physical exertion, an exercising person may breathe air in through the mouth.

(2) This bypasses the protection and humidifying of the nasal passages, and delivers more particulate matter to the lungs.Polluted air irritates the respiratory airways and this results in constriction (tightening) of the airways. This then leads to increased difficulty in breathing in a manner similar to what a person with asthma experiences.

(3) In addition, physical performance is affected as pollutants decrease the ability of the lungs to exchange gases such as oxygen, while there is also a reduction in the ability of the body to carry oxygen.

 

Are some people more prone to illness from polluted air?

Physical conditions such as those experienced with haze affect individuals differently.

(1) The general effects are those of irritation of sensitive surfaces exposed to the polluted air, primarily the eyes and the air passage of the nose and throat. This leads to itchy, watery eyes as well as a dry sometimes irritated throat. The latter may cause a cough or sneezing as the body tries to rid itself of the particles in the air. There may be some mild breathing difficulty.

(2) In people who are more prone to allergies such as hay fever or skin rashes, or who have asthma, haze conditions have a more pronounced effect. There is a higher level of irritability of the body to the particulate matter in the air, and this results in responses that may lead to greater breathing difficulty.

(3) Studies done in places which experience haze have recorded a higher incidence of medical problems in people with heart or lung conditions, as well as in the elderly.

 

What is PSI and how do we manage activity using it?

A pollutant standards index (PSI) was developed by the Environmental Protection Agency in the USA in association with the Clean Air Act. The PSI was a means of converting the level of pollutant concentration in the air to an index value for use by planners of physical activity. The PSI was originally captured in a table format as follows:

 

PSI index	Descriptor	General health effects	Cautionary statements
0-50	Good	No effect on general population	None required
51-100	Moderate	No or little effect on general population	None required
101-200	Unhealthful	Mild aggravation of symptoms among susceptible people; irritation symptoms in healthy population	Persons with existing heart & lung ailments should reduce physical exertion and outdoor activity. General population should reduce vigorous outdoor activity.
201-300	Very unhealthful	Significant aggravation of symptoms and decreased exercise tolerance in persons with heart & lung disease; widespread symptoms in health population	Elderly and persons with heart & lung disease should stay indoors and reduce physical activity. General population should avoid vigorous outdoor activity.
> 300	Hazardous	Early onset of certain diseases in addition to significant aggravation of symptoms & decreased exercise tolerance in healthy persons.	In addition to above, at PSI above 400, general population should remain indoors with windows and doors closed, and minimize physical exertion.

 

How do I interpret PSI in practical settings?

Certain things should be pointed out from a practical viewpoint:

(1) It must be realized that such PSI tables and advice on physical activity are based on the overall population. The PSI index values are thus arbitrary as some individuals may experience symptoms at even lower PSI levels while others may remain active longer at higher levels.

(2) Individuals and planners of physical activities must act with discretion when deciding on the type of physical activity to be undertaken as well as the exercise intensity and duration. It is prudent to lower the exposure to polluted air as well as reducing intensity to levels which still allow respiratory needs to be met through nose breathing (rather than breathing through the mouth).

(3) National broadcasts and advice given by the Ministry of Health should be studied carefully and applied judiciously to activities planned. When in doubt, consult an appropriate health authority. When conducting outdoor or indoor activities involving physical exertion, be particularly vigilant to individuals who have asthma, had a recent upper respiratory tract infection (cough, cold), or who are showing signs of being affected by the haze (reddened eyes, running nose, sneezing, sore throat, cough).

 

Where can I find more information on medical conditions related to exercise or physical activity?

Regularly updated information on sports medicine and sports science topics is available at www.sportzdoc.com where monthly articles addressing physical exercise-related issues are featured. You may address questions through the website contact details as well.