What does a UV rejection figure measure?
How much ultraviolet a filmed window stops, as a percentage. LLumar’s performance data sheet calls the column “Ultraviolet Protection” and measures it over 300 to 380 nm; every film on it, from 5% ATC to clear AIR 90, reads “>99”.
3M’s Color Stable brochure defines ultraviolet rejection as the share “rejected by the filmed glass” and notes that UV “contributes to the fading and deterioration of fabrics and leather.” Glassmakers often state the opposite number. AGC gives its privacy glass a UV transmission of 0.2 to 7% (ISO 9050), which is the light let through, not the light stopped.
How much UV gets through car glass without film?
More through the side glass than through the windshield. The Skin Cancer Foundation points out that a windshield is laminated and partly treated against UVA, whereas side, back and sunroof panes are tempered and let far more UVA pass.
Two studies put numbers on the gap:
| Glass | 2016, 29 cars (Boxer Wachler) | 2025, 34 models (Axelson et al.) |
|---|---|---|
| Windshield, share of UVA stopped | 96% on average | 99.25% |
| Side or driver’s window, share of UVA stopped | 71% on average; only 4 cars over 90% | 88.78% |
Darkness isn’t the variable. In a Skin Cancer Foundation expert column, a consultant from the International Window Film Association said a darker shade adds nothing to UV protection over a clear UV-blocking film.
Why UV rejection matters on a car in BC
Because the glass BC lets you film is the glass that lets the most UVA in. Any shade is allowed on the rear doors and rear quarters, and on a back window flanked by outside mirrors left and right, so everyone in the back can sit behind film. Drivers face the same issue up front: UV through side glass is associated with extra skin damage on the side nearest the window; in a 2010 study by Butler and Fosko, left-sided skin cancers outnumbered right-sided ones, 52.6% to 47.4%, an association rather than proof that driving was the cause.
The catch is the driver’s own window. Under MVAR s. 7.05(8) it can’t carry film of any kind, so even clear UV film there is off limits. Brookswood Tint applies it only for a customer who still wants it after hearing the risks: it is not road-legal anywhere in BC, the usual ticket is $109, and police can order the film stripped and the car inspected. The health questions are taken further in the car window film and UV guide.
Where UV ratings show up at Brookswood Tint
On every window film the shop installs: dyed ATC, ceramic IRX and clear AIR all carry LLumar’s over-99% rating, so UV protection comes with any rear package. If UV is your main reason and you don’t want the glass darker, LLumar AIR changes the look least. For families, UV protection for the family car sets out the rear-seat options, and whether tint stops interior fading covers the upholstery side.