Hazardous pollution at busy roads causes severe health problems

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The nature of Mauritius is still paradisic, though there are certainly “dark clouds at the sky”. Nevertheless, if you are not mindful when renting or buying a property, you can quickly get from paradise to hell. Every country has its specific characteristics to consider.

Hazardous pollutants at busy roads causing severe health problems

Beside the problem of money laundering, often involving real estate projects, we see in particular 3 key issues you should think about.

  1. Climate change, erosion and inundation, coastal setback and the influence on the value of properties
  2. Hazardous levels of pollution along busy roads causing severe health problems and even death
  3. Regular high noise emissions from dogs, parties and construction sites causing heavy disturbances, sleepless nights and severe health problems

Within the series “Important things to consider when buying apartments and houses in Mauritius” we will hence discuss these 3 important issues. After we intensively discussed Climate change, coastal setback and the the value of properties in the previous article, we will continue with topic No 2 in this article.


Another issue, often not in the mind of people considering renting or buying properties, is pollution. Though the air quality is in average not too bad in Mauritius, there are hazardous levels of pollution close to busy roads. This is of course an issue to be found in most countries, but due to lax regulations and lots of very old vehicles/buses, this issue is more relevant in Mauritius than in countries with more strict regulations.

Tremendous traffic growth in Mauritius

While the import of motor vehicles has been restrictively regulated in the past, a much more liberal regime has taken place a while ago. This resulted in a very heavy increase of motor vehicles on the island. Only in the period between 2007 and 2016 the number of registered cars has more than doubled from 99,770 to 202'696. The total number of motor vehicles has increased by 52% from 334'145 to 507'676. Up to 2015 the growth rate for registered cars has been constantly increasing, from 2015 to 2016 the growth rate stagnated at a high level of 7.6% per year.

Tremendous growth of traffic in Mauritius
Source: Republic of Mauritius, Ministry of Finance and Economic Development, Statistics Mauritius, Digest Of Road Transport And Road Accident Statistics 2016, Port Louis, November 2017, p.17

While there is a tremendous growth of motor vehicles on the roads, the length and the capacity of the road network has been significantly increased too. Since the development of roads can't keep up with the growth rate of motor vehicles, there is more and more congestion and traffic jam. But we don't have to bother too much about statistics here: Anyone who travels to work knows that the daily journeys have become a quasi-nightmare.

If the government will not go back to a more strict regime what the registration of cars concerns, the future looks very grim. Having a look at the experience of other countries with fully liberal car markets, there will be a continued heavy increase of motor vehicles along with economic growth. The Road Development Authority itself calculates with a yearly traffic growth rate of 6% between 2011 and 2020.1

Since the space on the island is very limited, especially at congestive spots such as Port Louis, Plane Wilhems and along certain coasts, and because many areas can't be used for roads due to geological issues, there is only one prediction for the future: Complete chaos. If you want to experience what that means, you can make a trip to the roundabouts in Trianon or Phoenix during rush hours. There is not only congestion and traffic jam at these hot spots, but at all (main) roads towards these roundabouts. Basically the whole area is one big traffic jam. Day by day.

The situation is furthermore complicated because of lack of alternatives. The pre-existing railway network has been destroyed long time ago – as we will see in the future probably one of the biggest mistakes of Mauritian history – and the planned railway projects are continuously pushed further into the future and/or drastically downscaled. As we could read in the previous article, new problems are awaiting too, as a significant amount of roads along the coasts will be jeopardized with climate change and coastal erosion.

Hazardous levels of pollution close to busy roads

Motor vehicles are an important source of urban air pollution. After adjustment for socio-economic status, negative effects on health were observed due to the proximity to roads. Exhaust emissions are an important source of traffic-related pollution and several epidemiological and toxicological studies have linked such emissions to adverse health effects. Road abrasion, tyre wear and brake wear are exhaust emissions, which become relatively important with the progressive reduction of exhaust emissions. Toxicological research is increasingly pointing out that such non-polluting pollutants could be responsible for some of the observed adverse health effects.

There are hundreds of scientific studies around who show that the level of certain pollutions close to busy roads is often hazardous.

Motor vehicles emit large quantities of carbon dioxide, carbon monoxide, hydrocarbons, nitrogen oxides, PM and substances that are classified mobile source air toxics such as benzene, formaldehyde, acetaldehyde, 1,3-butadiene and lead (where leaded petrol is still used as in Mauritius). Secondary by-products such as ozone and secondary aerosols (e. g. nitrates and inorganic and organic acids) are also formed further away from the road.

Especially very close proximity to roads – within 50m – showed a tremendous higher level of hazardous pollutants and adverse health effects. After 150-200m the levels are going down to levels similar to the more distant environment.2

Pollutant emissions from vehicles depend on the type of vehicle, the age, the maintenance conditions, the wear and tear of parts and the engine lubricants used.3 In countries such as Mauritius, where both regulations and controls are lax and where very old vehicles are on the road, the problem of dangerous pollutants appears to be even greater than in countries where most of the mentioned scientific studies have been carried out.

Adverse health effects due to proximity to busy roads

The problem about hazardous levels of pollution: You can't feel an immediate effect, except in very rare cases, where the air is really very very bad. In fact, most of the adverse effects are recognizable only months, years or even decades later.

There is scientific proof that hazardous levels of pollution close to busy roads create severe health problems and even can cause death.

Many studies have shown excess health risks in proximity to roads – after adjustment for a range of possible confounders, including socio-economic status. Excess health risks in proximity to roads includes cardiovascular mortality, respiratory mortality, cardiovascular disease, asthma, lung function reduction, lung cancer, birth weight problems, childhood cancer and lung cancer.4

Some scientific studies conducted about health effects due to proximity to busy roads:

  • Cardiovascular mortality (Gehring et al., 2006),
  • Respiratory mortality and traffic intensity in a 100-m buffer (Beelen et al., 2008a),
  • Myocardial infarction (Tonne et al., 2007),
  • Cardiovascular disease (Hoffmann et al., 2006),
  • Coronary artery calcification (Hoffmann et al., 2007),
  • Cardiac function-left ventricular mass index (van Hee et al., 2009),
  • Asthma (Morgenstern et al., 2007, 2008; Gauderman et al., 2005; McConnell et al., 2006a; Gordian, Haneuse & Wakefield, 2006; Kim et al., 2008),
  • Wheeze (McConnell et al., 2006a; Ryan et al., 2005; Venn et al., 2005; Gauderman et al., 2005; van Vliet et al., 1997),
  • Asthma hospitalization (Edwards, Walters & Griffiths, 1994; English et al., 1999; Lin et al., 2002; Wilhelm et al., 2008),
  • Lung function reduction (Sekine et al., 2004; Kan et al., 2007; Gauderman et al., 2007; Schikowski et al., 2007), birth weight (Brauer et al., 2008),
  • Childhood cancer (Savitz & Feingold, 1989; Pearson, Wachtel & Ebi, 2000), and lung cancer (Beelen et al., 2008b).

Busy roads in Mauritius

During morning peak hours all commuters are going to work to Port Louis or Plaines Wilhems. At the same time children are driven to schools by private cars, vans and school buses. Many workers who are employed at hotels, restaurants, residences and private houses are going the other way round. This cacophony is further enriched by heavy trucks and construction vehicles for the many construction sites all over the country. In the evening peak hours you can observe the opposite spectacle.

As a general rule roads with M, A and B letters are very busy. If you are going after road names, the Royal Roads and the Coastal Roads, which you'll find all over the country are typically very busy roads.

Difficult to say whether we have to discuss Port Louis in detail. In fact Port Louis there is congestion, traffic jam and pollution everywhere. At times Port Louis is one big traffic jam. From morning to evening more or less the same picture with the usual peak hours.
Here you'll find many very busy roads with heavy pollution. This is of course valid for the M1 and M2, but also for most roads with A and B letters. Some of the busiest spots are 2 roundabouts in Phoenix and Trianon and all the roads that lead to these roundabouts. During morning and evening peak hours, all these roads are very congested and have traffic jam. At these times it can take you an hour to move a kilometre or two. Basically most roads with A and B letters connecting one of these busy spots are at times one big traffic jam.
The B9 from Souillac to Black River gets busier the closer you get to Black River and vice versa. The A3 starting in Black River and going towards Cascavelle is one of the busiest main road of Mauritius. Especially during morning (7am - 10am) and evening peak hours (4pm - 6pm) there is very heavy traffic at the royal road (A3) from Black River over La Preneuse and Tamarin towards Cascavelle and the opposite way round. Due to several reasons (short cut for A3, growth) there has been a tremendous growth of traffic on the Avenue des Jacarandas in Tamarin, which is a very busy road during peak hours too.
There is at times significant traffic on the B9, A9 and the B8, but things certainly don't get as bad as at other places. Because the roads around Mauritius are often used for motor cycle and car trips during the week-end and because many people are travelling by cars and buses towards the beaches, the southern roads can at times be more busy during week-ends than during the week. The M2 connecting the airport is of course very busy at times and the area around Mahebourg can be very congested too.
There is traffic on the road, but the situation is certainly better than in the West and the North. You'll find some very congested city centres, Centre de Flacq being a very prominent example. As everywhere on the island, roads with A and B letters are usually quite busy.
All roads bearing the traffic from and to the north are typically very busy roads. This is of course particularly valid for the M2 and the A4. Being the touristically busiest part of the island, there is heavy local traffic too, what is in particular valid for all the A and B roads, but also for all roads at or leading to tourist hot spots.

A good indication is also the map from Michelin: Roads in red are typically very congested, roads in yellow often too.

Michelin Road Map

Conclusions

The uncontrolled growth of motor vehicles in Mauritius has created tremendous amounts of traffic, congestion, traffic jam and pollution. In close proximity to busy roads there are hazardous levels of pollution (ca. 50m) and in proximity there are significantly elevated levels (ca. 50-200m). Hazardous levels of pollution close to busy roads create severe health problems including deadly patterns such as cardiovascular mortality, respiratory mortality, childhood cancer and lung cancer. In Mauritius there are many very busy roads, in particular roads with M, A and B letters, Royal and Coastal Roads.

If you are looking to rent or buy a property, we recommend you to avoid locations less than 50m away from busy roads and to be careful about properties within the 50 - 200m range.

Especially if you are going to buy a property and you intend to stay there for longer periods of time, carefully evaluate the situation. Real estate agents will of course preferably meet you at times with low traffic. Optimally we recommend you to visit the place at different days and times to get a good impression about the real situation.

Further Reading:

  • Republic of Mauritius, Ministry of Finance and Economic Development, Statistics Mauritius, Digest Of Road Transport And Road Accident Statistics 2016, Port Louis, November 2017
  • World Health Organisation (WHO): Review of evidence on health aspects of air pollution – REVIHAAP Project, C. Proximity to roads, NO 2, other air pollutants and their mixtures, Copenhagen, 2013
  • Caderassen DORSAMY, Chansraj PUCHOOA, Road Development Authority: Alleviating Traffic Congestion Along The M1 Corridor: An Economic Perspective, October 2013
  • 1. Caderassen DORSAMY, Chansraj PUCHOOA, Road Development Authority: Alleviating Traffic Congestion Along The M1 Corridor: An Economic Perspective, Port Louis, October 2013, p.29
  • 2. Hitchins et al. (2000) reported a 50% decrease in PM 2.5 and ultrafine particles within 100–150 m of a road. A decay to background concentrations within as little as 50 m has been described for PM 2.5 mass concentration (Tiitta et al., 2002), although PM 2.5 tends to be more spatially homogeneous than ultrafine particles. Roorda-Knape et al. (1998) found that concentrations of black smoke, PM 2.5 , NO 2 , and benzene decreased to background concentrations within 100–150 m of a roadway (Roorda-Knape et al., 1998). In an environment with greater volumes of traffic, Zhu et al. (2002) found that ultrafine particles, black carbon, and total PM counts decreased rapidly in the first 150 m and then levelled off. PM 2.5 was found to be elevated only modestly (that is, in the range of 20%) near roadways. Zhu et al. (2006) suggested that distance-decay gradients extend to at least 500 m on the downwind side during night-time hours. Some studies concurrently measured such pollutants as NO 2 and volatile organic compounds (Roorda-Knape et al., 1998; Weisel et al., 2005) and carbon monoxide (Zhu et al., 2002; Zhang et al., 2005), to assess pollutant mix. Zhu et al. (2002) found that the decay of concentrations with distance on the downwind side of a highway was similar for ultrafine particles, black carbon and carbon monoxide – that is, a 60% to 80% decrease from roadside concentrations within 100 m. Gilbert et al. (2003) also found that NO 2 concentrations decayed with distance around a busy highway in Montreal, the greatest decrease occurring within the first 200 m.
  • 3. See World Health Organisation (WHO): Review of evidence on health aspects of air pollution – REVIHAAP Project, C. Proximity to roads, NO 2 , other air pollutants and their mixtures, Copenhagen, 2013, p.67ff
  • 4. See World Health Organisation (WHO): Review of evidence on health aspects of air pollution – REVIHAAP Project, C. Proximity to roads, NO 2 , other air pollutants and their mixtures, Copenhagen, 2013, p.67ff
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