The phrase "are more severe when" is correct and usable in written English.
It can be used to describe a situation where the severity of something increases under certain conditions or circumstances.
Example: "The consequences of the violation are more severe when repeated offenses occur."
Alternatives: "are heightened in cases where" or "tend to be worse if".
Casualties are more severe when it is dark than when it is daylight.
Furthermore, these changes are more severe when the area postrema is cooled.
These consequences are more severe when the mother is young (14 years of age or less).
Interference issues are more severe when NLOS wireless backhaul is used in unlicensed bands due to the contention for the channel among UEs of different technologies and operators.
As already evidenced for serum ferritin, it can be hypothesized that changes in hematological parameters are more severe when donations are repeated regularly, which could lead to iron deficiency.
In general, bullet wounds (and, in fact, any projectile wound) are more severe when the projectile yaws through tissue, when the projectile fragments or deforms (into a mushroom shape, for example), when the projectile is large, or when the projectile is travelling at high velocity [28].
The instability problems tend to be more severe when high speed compressors operate at partial speeds.
In certain cases, the consequences of irreproducible research may be more severe when it comes to biomedical research.
This yield degradation is more severe when the memristor device is used as a multi-valued memory element.
Whatever the reason may be, possible negative side effects of this type of surgery include persistent dry mouth and altered speech — which tend to be more severe when the whole uvula is removed.
Such an effect was more severe when the seeds were located above a 0.6 kg m−2 litter layer, although seedlings from seeds sown under the litter showed a growth reduction ranging from 58%to100%0% compared to the no-litter treatment.
