Haze is an aggregation of very fine, widely dispersed, solid or liquid particles or both in relatively dry air atmosphere which gives the air an opalescent appearance. The severity of haze condition is measured by PSI (Pollutant Standards Index) which is an index developed by the United States Environmental Protection Agency (USEPA) and is determined by the level of air pollutants. In general, healthy people should minimise outdoor activities when the PSI is greater than 200 whereas those who are of higher medical risk including children should minimise outdoor activities when the PSI is greater than 101.
Health Effects of Haze
The pollutant particles that make up haze can go deep into the lungs, and in some cases, enter into the bloodstream. The highest health risk is posed by the so called PM2.5 particulate matters that can penetrate right into the small air sacs in our lungs when inhaled.
Short-term exposures to haze particles (hours or days) cause asthma attacks, acute bronchitis, aggravate lung disease as well as increase the risk of getting respiratory infections. In people with heart problems, short-term exposures can be linked to possible heart attacks and arrhythmias. On the other hand, long-term exposures to hazy atmosphere have been associated with problems such as reduced lung function and the development of chronic bronchitis.
In addition, the health effects can be further categorized into local and systemic effects. Local effects can result in mild to severe eye, nose, and throat irritations. People with history of sinus problems or sensitive nose are more likely to develop nasal congestion, sore throat and coughing. Furthermore, incidents of skin irritations may be increased and people who are suffering from eczema or other skin diseases may encounter exacerbation of conditions. Systemic effects on the other hand can range from respiratory conditions such asthma attacks and worsening of heart diseases such as heart failure to increased risk of cancer.