York graduate student Mauro Aiello is busy building a better mousetrap, not to catch mice, but something just as pesky -- airborne chemicals.

    Aiello, an atmospheric chemist, is redesigning a machine that measures carbonyls, a class of chemicals found in common substances such as nail polish remover and formaldehyde.

    Atmospheric chemists are interested in assessing carbonyls for a number of reasons. "Some are toxic and carcinogenic," says Aiello, "and all of them contribute to the production of urban smog and ground-level ozone." Ozone is useful at high atmospheric levels in blocking out ultraviolet rays, but at ground level causes health problems and can "burn" crops.

    Carbonyls are also produced by the breakdown of emitted chemicals that are already present in the air. "They are there in minute quantities, ranging from less than one part per trillion in very clean air, to one part per billion in polluted air," says Aiello.

    The instrument he's developing will combine micro-scale sampling with micro-chromatography. "It will be capable of detecting smaller amounts of carbonyls in a shorter time, and at reduced cost, compared to today's techniques," he says. The instrument will eventually be used to measure carbonyls in field studies.

    "It's important to understand the chemistry causing these problems so we can make educated decisions about what emissions to reduce, and why."