ABSTRACT
Urban air pollution in the tropics is rapidly increasing and will lead to thousands of preventable deaths in the absence of stringent regulations and remedial measures. The vast majority of the air pollutants appeared to come from industrial and residential sources instead of conventional biomass burning which has historically driven air pollution in tropical regions. In addition, enhanced transportation further contributes significantly to the degradation of air quality. Major pollutants of concern include sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3) and particulate matter (PM10 and PM2.5)—all of which consistently violate the air quality standards except SO2, which reduced drastically after the use of unleaded gasoline and promotion of efficient engine designs. These pollutants when emitted in the atmosphere follow similar modes of deposition (wet, dry and occult). After deposition, these impose a severe threat to plants exposed, from visible injuries to altering their physiology and biochemistry and ultimately impacting the biomass and yield of both crops and trees. One of the crucial concerns of air pollution is the decline in food security as it negatively affects crop yields, especially in the tropics, which includes the highest food-producing countries. The impacts of common air pollutants on the ecophysiology of the dominant trees and major crops of the tropics are discussed in detail in this chapter. Trees were found to be comparatively less affected than crops in terms of biomass and yield, while visible injury was found similar and equivalent for a particular pollutant. Vigna radiata was found to be more susceptible among the studied crops, while Psidium cattelianum was most affected among the assessed trees under air pollutant stress.
