私醫聯招 英文歷屆試題｜第 187 題

If we want to live longer, we can no longer afford to inhale air contaminated with particulate matter. Particulate matter—also known as particulates—is microscopic solid or liquid matter floating in the Earth's atmosphere. Sources of particulate matter can be natural or man-made. Particulates which occur naturally may originate from volcanoes, dust storms, or forest fires. Human activities, such as the burning of fossil fuels in vehicles, coal combustion, and various industrial processes also generate significant amounts of particulates.

Fine particles, with a diameter of 2.5 micrometers or less, are the most lethal form of air pollution because they are able to penetrate deep into the lungs and blood streams unfiltered, which in turn may cause permanent DNA mutations, heart attacks, and premature death. In addition, particulate matter exposure is also linked to an increased risk of stroke by its narrowing effects on the arteries.

Particulate matter can clog minute pores of plant leaves and interfere with photosynthesis functions. It has been found that high particulate matter concentrations in the atmosphere can lead to stunted growth or mortality in some plant species.