IN THE meantime, perhaps Metro Manilans should start considering wearing masks over their noses and mouths, at least when they venture out in the streets. Galang herself would most probably agree that the suggestion should be taken seriously by those who are exposed to longer periods of time to the city's filthy air, such as jeepney and bus drivers and ambulant vendors.

According to an epidemiological study by the UP College of Public Health, the prevalence of chronic obstructive pulmonary disease is 32.5 percent among jeepney drivers, 16.4 percent among air-conditioned bus drivers and 13.8 percent among commuters. It also found that incidences of all four of the disease's characteristic symptoms—chronic cough and phlegm, wheezing and shortness of breath—to be significantly higher among jeepney drivers.

Schoolchildren and child vendors studied by the same UP team showed that almost 80 percent of these children have blood lead levels higher than the 10 ug/dl limit of toxicity. At that level, lead in a child's blood has severe effects that include lower IQ, impaired hearing, and impaired growth. These numbers are alarming, say the doctors who did the study, as the effects that would manifest are more chronic in nature.

Experts say the three main sources of air pollution are mobile sources (vehicles); point sources (like industrial firms and smoke stacks of power plants, hotels, and other establishments); and area sources (smoking, burning of garbage, dust from construction).

Elements released by air pollution sources vary, and include dust, sulfur dioxide, total oxidants, nitrogen oxides, ozone, lead, and carbon monoxide. But recent studies on the effects of chronic exposure to air pollution have singled out particulate matter as the pollutant most responsible for the life-shortening effect of dirty air.

The kind of damage done by these particulates is strongly linked to particle size. Small particles, such as those from fossil-fuel combustion are likely to be most dangerous, because they can be inhaled deeply into the lungs, settling in areas where the body's natural clearance mechanisms cannot remove them. The constituents in small particulates also tend to be more chemically active and may be acidic as well, and therefore more damaging.

Health experts explain that children are more susceptible to illnesses brought about by air pollution because when they exercise, they tend to breathe through their mouths. Mouth breathing bypasses the natural filtering of air pollutants by the nose and allows large volumes of polluted air to affect the more sensitive areas of children's lungs, which are still developing.

On a global basis, estimates of mortality due to outdoor air pollution run from around 200,000 to 570,000, representing about 0.4 to 1.1 percent of total annual deaths. As the range of these estimates indicates, quantifying the toll of outdoor air pollution is difficult. But the health impacts of urban air pollution seem likely to be greater in some of the rapidly developing countries where pollution levels are higher.

The World Bank has estimated that exposure to particulate levels exceeding standards set by the World Health Organization (WHO) accounts for roughly two to five percent of all deaths in urban areas in the developing world. In Jakarta, one recent analysis estimated that some 1,400 deaths could be avoided each year if particulate levels were brought down to WHO standards. So too could 49,000 emergency-room visits, and 600,000 asthma attacks, it said.

Back in Pasig, another study by the UP College of Public Health and the ADB notes that hospital admissions for pneumonia, especially among children up to four years old, are up, as are those for other respiratory illnesses like bronchitis. Fortunately for Pasig, there are residents like Pachot Ramirez who have vowed to help improve the air quality there, even if that sounds rather impossible given the city's sorry environmental state.

Ramirez for one believes that cleaning up the air is as much the responsibility of every family as it is that of the government. "It's a matter of principle," she says. "Since it's your neighborhood, then keep it clean." In her barangay, where she is a community volunteer, residents turn some of their trash into compost. All the spaces that they could manage to free, they plant with flower-bearing trees and vegetables.