The rules on tinted and reflective car windows are not clear
The Sunday Nation
Nairobi,
18 May 2014
When the Inspector General (IG) of Police, David Kimaiyo, instructed his officers to impound vehicles with tinted windows this week, Kenyans went abuzz pointing out that there is no law against it. The IG then clarified that his directive was only affecting public service vehicles since the “Traffic Act Cap 403 S54 A 1&2 is clear on tinted PSV windows & Section 30 on windscreen & windows of [all] motor vehicles with reflective properties”
I checked that law and, unfortunately, it is
actually not clear! This is what it says in the sections that the IG
referred to: “The windscreen and windows of every motor vehicle shall be
kept free from the application of any material which has, or is capable
of having, reflective properties; …A
person shall not drive or operate a public service vehicle that is
fitted with tinted windows or tinted windscreen…‘tinted’ means
shaded, coloured or treated in a similar manner so that the persons or
objects inside are not ordinarily seen clearly from outside.”
It sounds clear but from a
scientific point of view it is quite vague; for starters, even clear
glass is reflective – you can see your image in it quite easily, can’t
you? Secondly, most vehicles come
out of the factory with faintly tinted windows. The question then is,
how faint is allowable by this law?
To be clearer, the rules
should state the limits of reflectance and transmittance of the glass.
That is, what minimum amount of light must pass through the window glass
and what maximum is allowed to reflect?
I saw similar rules from a
different country and they stated that the glass must allow at least 35%
of light to get through and must not reflect more than 21%. That is
something that can be tested scientifically; but it is also not perfect…
Which light is the law
talking about: Green, yellow, read or what? So-called white colourless
light comprises of all the colours of the rainbow. And they are not
seven! They are infinite in number.
The nature of glass is that
it reflects and transmits different percentages for different colours.
It has higher reflectance for longer wavelength (reddish colours) that
for shorter ones (bluish colours).
This is the reason why a car
gets very hot inside when left under sunlight. It is also the working
principle of a greenhouse. Once sunlight gets inside, it is absorbed by
the items in there; as a result they warm up and emit infra-red “light”.
More than 50% of this
infra-red is reflected back into the car by the glass – it is therefore
trapped and cannot get out. Consequently, the car continuously
accumulates the heat and becomes much hotter than the surrounding.
With these
technicalities in mind, a good lawyer can argue in court that the rules
on tints and reflective car windows are not clear and are therefore
difficult to obey. It would be advisable for the Transport Ministry to
revise the rules before we get to that.
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