INTRODUCTION
The heavy movement of vehicles along a highway is a major source of air pollution. These vehicles, through their exhaust pipes, introduce harmful materials into the atmosphere. In the course of vehicular movements, non-combustible emissions such as road dust and tire wear are also emitted into the atmosphere. Similarly, some of the emissions introduced into the air react with other substances to form secondary pollutants. While the world is focusing on improving global air quality through improvements in fuel choices for the transport sector, it is important to examine the trails of this moving pollution source especially in Nigeria.
BACKGROUND
Nigeria is a developing country with poor and limited public transport options. This means that individuals with a sizeable disposable income are likely to try to purchase their own cars to ease the burden of transportation. This, in addition to the economic growth and often busy activities that characterize urban areas in Nigeria have increased the number of vehicles that ply her roads. Majority of these vehicles are second-hand vehicles imported into the country. These vehicles, in asides being heavily dependent upon unsustainable fossil fuel options, have no catalytic converters nor air filters. The catalytic converters and air filters are usually removed before export to developing nations (Raje et al., 2018). It is important to note that while the increasing number of fossil-driven vehicles drive up air pollution levels, the social dichotomy between the urban-rich and urban-poor also widens. Economic competitiveness and living quality also reduces as congestion and rate of severance from loved ones/workplaces increases. Urban congestion, air pollution, increasing social dichotomy are basic contributors to social and environmental unsustainability (UN, 2016).
Lagos state as a case study
Lagos state is located in the South-Western part of Nigeria (between longitude 20 42’E and 32 2’E; and latitude 60 22’N and 60 2’N) and has a landmass of 3,577 km2. Lagos state is the most populous city in Nigeria and its population has been estimated to have hit the 35 million-mark in 2020 (Lagosstate.gov.ng). Although the State government has been making considerable progress and investments towards strengthening the transport system, the persistent traffic congestion leaves social, economic and environmental degradation in its trails. To understand the effect of traffic congestion of residents, an online survey was conducted and assessed. Majority (74.4%) of respondents are between 31-50 years old.
Despite the fact that 63.2% of respondents use public transportation, 89.5% of respondents experience traffic congestions. This suggests that introducing mass transport systems into the city would not be enough to control traffic congestion and hence, traffic pollution. Developing a green and sustainable transport system/infrastructure in Lagos state is an important and a major step towards a sustainable city.
While 87.2% of respondents experience traffic congestion on their way to work/school, these traffic congestions last for 30 mins and above for 75% of respondents. This points to the fact that where sustainable environmental policies are not adequately incorporated into road transport infrastructure, road users become exposed and threatened by accompanying environmental pollutants/toxins for extended periods. These adverse environmental impacts arise from environmental degradation factors like soil erosion, flooding, solid waste, noise pollution, gravel pits and road run-offs in addition to the well-known exhaust emissions by vehicles.
Exposure to these environment degrading factors leaves various human health challenges and discomfort in the trails of vehicular traffic pollution. While exposure to air pollutants may be the most obvious/expectable threat to human health. From our survey, almost half of the respondents reported increased body pains, 41% indicated that they are experiencing more stress-induced illnesses, and 20.5% reported discomfort from the hot weather as 79.5% of respondents, more often than not, have been forced to walk long distances due to vehicular traffic congestion.
Another threat vehicular traffic congestion leaves in its wake is severe economic loss in time and money. The waste of valuable time caused the most stress for 61.5% of respondents. Heavy traffic congestion, high rates of walking, poor transportation infrastructure, and the polar distribution of jobs and affordable housing lead to low employment/economic accessibility. For instance, people arrive late for work and often in a poor state of mind thereby hindering productivity. Business owners practically lose customers due to the congestion just as some people avoid scheduling work appointments for weekdays which reduces the length of productive time. Similarly, 61.5% of respondents stated that the traffic congestion that has characterized the city has influenced their finances badly as people spend a huge chunk of their earnings on fuel/vehicle servicing and inflated transportation fare. With heavy traffic congestion comes high cost of fares as commercial bus drivers hike transportation fares arbitrarily. Sometimes, people have to opt for motorcycles to beat the road traffic although these are usually more expensive.
Without adequate mitigation measures or restorative interventions against vehicular traffic congestion/pollution comes a cycle of increasing exposure to air pollution, fuel waste, health risks and physical congestions, time and economic losses as well as social disconnect. Looking briefly at the latter, vehicular traffic congestion and pollution can result in social severance. For example, only 7.7% of respondents stated that traffic congestion doesn’t prevent them from visiting family and friends. Similarly, only 2.6% of respondents stated that road traffic congestion doesn’t prevent them from attending social events .
Despite the deteriorating air quality and other attendant effects of road traffic congestion, less than half of respondents have opted for carpooling as a result of road traffic congestion. Similarly, even though people have been forced to walk long distances due to traffic congestion, non-motorized transport systems like cycling and walking are hardly considered as options. This is probably due to lack of dedicated infrastructure like green walking routes and incomplete pedestrian connectivity.
Although the Lagos State Government has made major infrastructure investment through the introduction of the Bus Rapid Transit (BRT) system and improvements in road conditions and traffic management, sustainable environmental policies have not been adequately incorporated into the road transport infrastructure. The deficient transportation infrastructure leaves environmental, social and economic degradation in its trails.
Conclusion
While political and strategic interventions are required to ameliorate vehicular traffic congestion impacts, mitigation strategies may be manifold and circuitous. In addition to high cost of land and energy as well as unsafe transport services, inadequate transport management institutions have been identified as major causes of road traffic congestion in urban cities (Raje et al., 2018). In fact, 43.6% of respondents attributed the cause of road transport congestion to the activities of road transport operators/management.
Therefore to make cities inclusive, safe, resilient and sustainable ( in accordance with SDG 11), there is need for a modal shift and behavioural change amongst the populace just as the government needs to focus on infrastructural improvements and adoption of clean energy options for the transport sector.