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against light pollution


The municipalities of the Mont-Mégantic International Dark Sky Reserve have one of the most important roles in preserving the starry sky and nocturnal ecosystems of the region.

Not only do they manage public lighting, responsible for around 50% of a city's light emission, but they are also ensuring the compliance of all private outdoor light sources with the regulations controlling exterior lighting.

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In the Mont-Mégantic International Dark Sky Reserve, the regulations controlling exterior lighting are divided according to the 3 regional counties of municipalities: Sherbrooke, Haut-Saint-François and Granit.

In addition, the municipalities of the Haut-Saint-François and Granit RCMs are distributed in 2 zones, depending on whether they are closer or farther from Mont Mégantic. Whether they are at the foot of the mountain or at the edge of the Reserve, each municipality has an important role to play against light pollution.



*additional and exact specifications can be found inside the regulations documents (french only).

Résumé réglementaire


Emit less than 1% of the luminous flux above the horizon,

or less than 2.5% of the luminous flux if the luminaire is installed at a height less than:

  • 3.5m in zone 1 of the Haut-Saint-François and Granit RCMs.

  • 5m in zone 2 of the Haut-Saint-François and Granit RCMs,

  • 7m in Sherbrooke.


The use of visors or the installation of the luminaire under a canopy may be compliant if they meet the maximum percentages of light emitted above the horizon.


Light sources of 2200 K and less (10% blue light* and less) are required for all exterior usesexcept for the following :

For the uses specifically identified below, the light sources can reach a maximum color temperature of 3000K (or 20% blue light*) :

  • outdoor commercial display area

  • non-residential building entrance (only in Sherbrooke)

  • light source emitting less than 1000 lumens (only in Haut-Saint-Francois and Granit RCMs)

For the uses specifically identified below, the light sources can reach a maximum color temperature of 4000K (30% blue light*) :

  • gas pumps

  • sports field (*exemption in Sherbrooke)


Colour temperature, expressed in Kelvin ( ), is used to refer to the hue of a light source. This value can be found on the source packaging or in the luminaire photometric report.


The higher the colour temperature, the greater the amount of blue light.

Percentage of blue according to the type of source:

  • Amber LED - 0% blue

  • PC-Amber LED (1800K) - 2% blue

  • LED 2200 K - 10% blue

  • LED 2700 K - 16% blue

  • LED 3000 K - 22% blue

  • LED 4000 K - 30% blue

  • High Pressure Sodium (2200 K) - 8% blue

  • Halogen (3000 K) - 16% blue

  • Metal halide (4000 K) - 35% blue

* The percentage of blue light represents the light emitted in the range of wavelengths between 405 and 530 nanometers compared to the range of wavelengths between  380 and 730 nanometers.


The spectral power distribution of a source or a luminaire is available with its photometric report.

[ 405 to 530 nm ]   =   percentage of blue light

[ 380 to 730 nm ]


The installation of exterior lighting devices must correspond to a specific use, or an equivalent task, and must comply with the lighting levels prescribed in the regulations.

These maximum lighting levels are modulated according to the type of use so as to ensure the necessary visibility in accordance with the needs of a particular task.

For example, levels for street lighting, outdoor commercial display areas, storage lots, parking lots, and sports fields are all listed in regulations. For the uses requiring a large amount of light, a photometric study and point-by-point calculation are generally required.

For lower intensity installations, such as residential use, it is possible to use the total light emitted by the luminaires (in lumens) to determine compliance, within the limits prescribed in each regulation.




Haut-Saint-François and Granit RCMs:

  • Lights off, including signs, after 10 p.m. or outside of operating hours.

  • Outside of operating hours, exterior lighting for outdoor commercial display and handling/work areas must :

    • be turned off;

    • reduced to the equivalent light levels of storage areas (10 lux);

    • or reduced by at least 75%.

  • Switch-off is not mandatory for:

    • Pedestrian areas

    • Streets

    • Building entrances

    • Storage lots

    • Monuments and landscaping


  • Lights off, or reduced by at least 50%, after 11:00 p.m. or 30 minutes after hours of operation. This also applies to signs.

  • Complete switch-off of lighting fixtures for outdoor sports and playgrounds 30 minutes after the end of the activities taking place there.

  • Switch-off and dimming is not mandatory for :

    • Building entrances and perimeters

    • Parking lots of multifamily housing

    • Streets




“Do LEDs reduce light pollution?”

No, LEDs can reduce power consumption, but not necessarily light pollution. It is possible to choose amber or yellow coloured LEDs which will reduce the impact of light at night.


Many municipalities in the MMIDSR have been using these amber LED luminaires (with a colour temperature between 1800K to 2200K) for several years for public lighting. The light appearance of amber LEDs is similar to the often used High-Pressure Sodium luminaires.


However, the majority of available LEDs are often too white and lead to an increase of light pollution. White LED lights are not allowed in the MMIDSR for exterior lighting, except for a few specific types of use. These exceptions are identified in the regulations.


"Will reducing outdoor lighting risk reducing safety?"

No. Several studies have shown that reducing lighting does not have a negative impact on safety and that increasing lighting does not directly result in a positive effect on safety either.

Serious studies have shown that there is no direct link between night lighting and safety, whether it is for road safety as well as for crime. It is important to go beyond the myths and our own impressions.

In addition, the improper use or installation of light fixtures may make the situation worse. Bad lighting can create glare and strong contrast that will affect the good visibility of the nocturnal environment.


“Is a 'Dark Sky' light fixture automatically suitable for the Mont-Mégantic IDSR?”

Several light fixtures are identified as "dark sky", but not all of them are suitable for use in the Mont-Mégantic International Dark Sky Reserve.


The Mont-Mégantic IDSR enjoys very high standards of protection of the night environment which are often ahead of usual practices and guidelines. Several "dark sky" fixtures emit light that is too white and rich in blue. It is therefore important to make sure to choose lighting that meets the regulations of the region.

The intensity of a fixture must also be adequate according to its type of lighting task.


In addition, several of these labels are not official certifications but simply identifications but the manufacturer.


"Who makes sure that the regulation on outdoor lighting is applied?"

The municipal inspectors are responsible for enforcing the regulations 

in the Mont-Mégantic IDSR.


The installation of new lighting or the modification of existing lighting must be made following the requirements of the regional regulations.


Most often, it is when applying for a building permit that the assessment is made. Certain cases of inadequate lighting are also brought to the attention of inspectors by complaints from citizens.

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