Poor air quality, also known as “haze”, “smog” and “air pollution”, can negatively impact one’s health.
Haze is caused by dust, smoke and other pollutants that obscure the normal clarity of the sky. It most often occurs when the air is relatively dry and when weather patterns do not allow pollutants to disperse.
Smog results from a mixture of air pollutants, mostly ground-level ozone, which have chemical reactions in the air. Many of these pollutants are created by burning fossil fuels.
Some groups are especially vulnerable to problems caused by polluted air. These include older people, children, and anyone with underlying chronic health problems such as heart disease, emphysema, bronchitis or asthma.
The chemicals in polluted air can cause breathing passages to become inflamed, decreasing the lung capacity and resulting in wheezing, coughing, shortness of breath and even pain upon deep inhalation. Polluted air can also irritate the eyes and nose, and may interfere with immune system function. Certain people, for reasons as yet unknown, are particularly sensitive to ozone even without any underlying risk factors.
Long-term exposure to pollution can result in reduced lung function, particularly in children.
There are several systems used to measure air quality:
• The Pollution Standard Index (PSI)
• The Air Quality Index (AQI)
• The Air Pollution Index (API)
The following table shows air quality reading levels, their possible health effects and suggested precautions:

Limiting exposure to polluted air is the best way to avoid these problems. Techniques vary depending on the severity of the problem. When air quality is poor, it may be advisable to avoid outdoor physical activities, as exertion causes people to breathe deeper and quicker. If you do not know the air rating, a general guideline is to avoid outdoor exercise if the edges of nearby buildings cannot be seen clearly due to polluted air. During particularly bad periods, you may want to wear a mask while outside. N95 or equivalent masks are effective, however should only be used after medical evaluation.

While inside, keep doors and windows closed, and use an air conditioner on ‘recirculate’ if possible. If the air quality is frequently problematic, you may consider using an air cleaner. Several types are available, including fixed and portable devices. If air quality is predicted to reach hazardous levels on multiple consecutive days, those who are elderly, have already developed symptoms or have underlying conditions may wish to consider moving temporarily to a region with better air quality.
Southeast Asia has regular occurrences of haze, which are caused in part by land and forest fires in Indonesia.

SINGAPORE
Singapore experiences annual occurrences of haze problems, usually between May through October. Unhealthy air conditions are more likely if forest fires are burning in the region and the smoke blows in from prevailing Southwest Monsoon winds.
Singapore’s National Environment Agency (NEA) uses standards set by the United States Environmental Protection Agency to gauge air quality (click here for the EPA standards). NEA monitors air in Singapore on an ongoing basis, measuring major pollutants like sulphur dioxide, nitrous oxides, carbon monoxide, ozone, hydrocarbons and particles that are able to be inhaled (called “respirable suspended particles” or PM10, as they are 10 micron or smaller in size).

MALAYSIA
Malaysia suffered haze emergencies in September 1997 and August 2005. An emergency is declared when the air reaches a rating of over 500. API ratings are published daily.
Typically, during haze emergencies non-essential government services are suspended and ports are closed. Schools may also close and flights may be cancelled due to visibility issues. Some activities may be temporarily prohibited in both the private and commercial realms.

CHINA
Major cities such as Beijing and Shanghai experience high levels of air pollution on an ongoing basis, partially due to rapid economic and industrial development. Both of these have contributed to increased coal burning. Beijing is significantly affected, due to increasing motor vehicle traffic, dust from construction projects and sandstorms in northern China, which distribute particulates into the city’s air.
China publishes daily reports on air quality in over 80 cities, based on an Air Pollution Index (API). The Beijing Municipal Environmental Protection Bureau also reports on air quality in Beijing (in Chinese).

INDONESIA
For centuries, the geographical resources of the Indonesian archipelago have been exploited in ways that fall into consistent social and historical patterns. One cultural pattern consists of the formerly Indianized, rice-growing peasants in the valleys and plains of Sumatra, Java, and Bali; another cultural complex is composed of the largely Islamic coastal commercial sector; a third, more marginal sector consists of the upland forest farming communities which exist by means of subsistence swidden agriculture. To some degree, these patterns can be linked to the geographical resources themselves, with abundant shoreline, generally calm seas, and steady winds favoring the use of sailing vessels, and fertile valleys and plains–at least in the Greater Sunda Islands–permitting irrigated rice farming. The heavily forested, mountainous interior hinders overland communication by road or river, but fosters slash-and-burn agriculture.
Each of these patterns of ecological and economic adaptation experienced tremendous pressures during the 1970s and 1980s, with rising population density, soil erosion, river-bed siltation, and water pollution from agricultural pesticides and off-shore oil drilling.
The 1997 Indonesian forest fires in Kalimantan and Sumatra caused the 1997 Southeast Asian haze. It was a large-scale air quality disaster. The total costs are estimated at US$9 billion to health care, air travel and business. In 2013 the air quality sink lowest in 15 years in Singapore due to smoke from Sumatran fires. Singapore urged Indonesia to do more to prevent illegal burning.