Air pollution is an under-appreciated concern and that the impacts of air pollution is poorly understood. Sri Lanka faces a rapid rise in pollution from internal sources and from trans-boundary sources in the continent to the North. Air quality problems are increasing day by day due to the rapid rise in emissions of particulate matter and noxious gases from vehicular traffic, industrial emissions particularly from thermal power generation plants, rapid urbanization and trans-boundary transport of atmospheric contaminants from the Asia continent.
Particulate matter is the primary pollution of concern in Sri Lanka because it has consistently exceeded WHO guidelines. SO2 has shown increasing trends although they are still close to USEPA guidelines from 1997 to 2003. Annual NO2 levels, on the other hand, have consistently complied with WHO annual guidelines as well as annual USEPA limits.
Emissions from Transport:
Trends in energy consumption show increases in petroleum consumption compared with other renewable sources such as biofuels and hydropower. The country has also seen rapid motorization (e.g., doubling of the motor vehicle fleet in one decade from 1991 to 2000). Sri Lanka’s Ministry of Environment estimated in 2011 that emissions from motor vehicles account for 55-60% of air pollution, while 20-25% is due to industries and 20% is from domestic sources. The number of vehicles too is rising and although recently emission testing has been mandated, the rise in emissions from 3-wheel auto-rickshaws has aggravated air quality, particularly in urban settings.
Emissions from Power Generation:
The share of thermal power generation is increasing due to rising demand and reductions in generation by hydro-electricity due to the declining streamflow. Since 2011, there has been a rise in installation of electricity generation plants including a 900 MW coal power plant at Puttalam.
Impacts of Air Pollution:
The impacts of the increasing air quality issues on the environment and climate are poorly understood. Preliminary studies on the impact of noxious gases and particulates on the atmospheric chemistry at ground level points to deleterious impacts on land and water quality. There are no studies on the impact of particulates on cloud formation and modulation of rainfall. The trans-boundary emissions from the Asia continent to Sri Lanka is also becoming a significant source of pollution at higher elevations.
Monitoring and Mitigating Air Pollution:
Managing the environmental impacts of transport systems and electric power generation are two defining challenges of contemporary times across the world as society tries to manage local atmospheric pollution and the global commons. There is a particular need for attention to air quality in tropical countries such as Sri Lanka as there is limited capacity to monitor air quality and implement mitigation steps. In Sri Lanka, industrialization and urbanization activities are centred on the coast of the Western Province comprising Gampaha, Colombo, and Kalutara districts. There is long-range transport of these pollutants into the mountains (which reaches an altitude of 2 km) as carried by the summer monsoon wind streams from April to October.
The focus on improved implementation and enforcement of laws and action plans should be a priority since implementation of previous action plans have been slow.