Air pollution is world’s largest single environmental health risk. It has both acute and chronic effects on human health, affecting a number of different systems and organs of human body. WHO (2014) estimated that approximately 7 million premature deaths are attributable to air pollution exposure.  Health effects of outdoor air pollution have become a growing concern in most of the capital cities in Sri Lanka. Primary source of ambient air pollution in Sri Lanka is considered to be a vehicular exhaust which in City of Colombo is estimated to be at 55% of its total emissions

Status of Air Quality in Colombo
Air quality monitoring data collected through passive sampling technique by National Building research organization (NBRO) reported that at some traffic congestion prone areas in Colombo city, the levels of harmful pollutants especially particulate matter (PM) have exceeded permissible limits which was published under the regulations in the Gazette Notification No. 1562/22 on 15.08.2008. This is also beyond the interim targets published by world health organization (WHO).

Vehicle Emission testing 

As vehicular emission is considered to be the primary source of urban air pollution, VET program has been initiated by government in year 2008 aiming to control the level of harmful exhausts from vehicles. Establishment of VET program is a significant milestone in Air quality management in Sri Lanka. According to our available statistics, the number of vehicle emission tests carried out at VET centers increases considerably year by year with the addition of new registration into existing vehicle fleet. In year 2020, number of initial tests done have reached more than 5.2 million. This does not include some vehicles including the exempted categories and those of Tri forces. As per the testing data, nearly 20% of the vehicles fails at the initial testing and out of the failed vehicles 50% are motorcycles and motor tricycles. After the tests, users are expected to maintain vehicles properly. However, according to our roadside inspections, even vehicles especially buses and long vehicles which have passed emission test are found running smoky on roads because of lack of subsequent due maintenance by users.

Who are the most vulnerable? 

Emissions from vehicle’s tail pipes contain a heterogeneous mixture of pollutants and these emissions as well as street dust suspensions can be transported into vehicles itself with an open window and then affects the passengers inside. It further affects users of motorcycles and three-wheelers running behind the smoky vehicles. Non-vehicle users including pedestrian and other roadside users are also forced to inhale this same polluted air and so cannot be escaped from effects of air pollutants. Urban dwellers report higher prevalence of respiratory illnesses since they spend more time on roadsides. All of them are thus exposed to higher concentration of PM, SO2, CO, NOx and have all associated common respiratory symptoms and cardiovascular diseases.

According to scientific studies, the particle concentrations near major traffic roads are 10 times higher than its levels of urban background. Moreover it is estimated that the highest pollutant levels prevail within 150 m from roadways and remain high up to 300 m away from the roadway. Thus, the people living or working near major urban roads are likely to be exposed to high ultra fine particle levels.

Partial combustion and loss of energy

Ideally, if combustion process of ICE is perfect (stoichiometric combustion), the exhaust gases should only be carbon dioxide (CO2) and water vapor (H2O). In reality, mainly due to incomplete combustion, the exhaust gases contain many pollutant emissions. Most significant are PM, SO2, CO, NOx. High concentration of them in exhaust can be attributed to reasons such as improper air–fuel ratio, ignition or injection timing, turbulence in the combustion chamber, combustion temperature, lubricating oil composition and emission control system. Quality of fuel also determines the characteristics of emission. 

According to the International Agency for Research on Cancer (IARC) under the WHO, Diesel exhaust has been classified as carcinogenic to humans (Group 1, IARC) while Gasoline engine exhaust is classified as possibly carcinogenic to humans (Group 2B, IARC).

High emission from vehicles mostly occurs under un-burnt and partially burnt fuel conditions. High emission means not only a waste of energy and but leads to loss of money due to less efficiency and poor performance. Therefore, control of emission is important as it results in reduction in unnecessary fuel consumption by the engine and helps saving of money and preserving of air quality. Yearly emission test helps vehicle users to know the actual engine performance and yield the above benefits. However, among other things in order to accrue all these benefits, proper periodic maintenance of vehicle in between emission tests by the user is very much essential. Many of smoky situations can be easily resolvable.  

Non replacement of clogged air filters and fuel filters, improper fuel pressure adjustments, excessive loading are common reasons for smoky vehicles. Improper mixture of 2T with fuel in 2 stroke two wheelers and three wheelers also contribute to producing of too much particulate in exhaust. Practicing ECO style driving devoid of aggressive driving is a good way to reduce fuel burning and emitting of smokes in any type of vehicles under any stage. In addition, prevention of un-prescribed fuel helps not only emission reduction but also prolong engine useful life

Contribution as an environmental enthusiast 

Vehicle emission testing is carried out to ensure that vehicle running on roads emit emissions within permissible limits. Compared to allowable emission levels in many countries in South East Asian region, prevailing limits in Sri Lanka are comparatively low. Therefore, to achieve expected outcome of VET program by minimizing adverse effects guaranteeing public well-being, Vehicles on roads must strictly adhere to the prevailing limits stipulated under environmental regulations. In this line, vehicle users are required to keep the vehicle maintenance to the recommended condition throughout the year. Poor performing vehicles badly poses threats not only to the health of users itself, but also the health of others. 

Considering the fact that breathing of quality air is a basic right of the citizen in the country, general public should be alert of the pollutions happening around them. VET as regulatory body facilitates receiving complaints from environmental concerned public of any such smoky vehicles running on roads. It receives such public complaints from a public complaint platform comprising of email, WhatsApp or Viber. (0703500525)   

Commitment of VET program 

Since the inception, VET program contributed in many ways to enhance ambient air quality. Considering the importance of measuring ambient air quality, it procured automated ambient air quality monitoring station (AAQMS) for NBRO and CEA. These expensive equipment helps the stakeholder organizations in their attempt to establish island wide Ambient Air quality monitoring & Evaluation system.

VET program also provided funds for undertaking researches, studies and surveys in the field of ambient air pollution through universities and other research institutes to help identify mitigation activities to improve Air quality.
With a request, users of vehicle can also obtain emission history of their vehicle which includes, among other parameters, odometer reading at the testing time.