Worldwide ICH Stability Study Climatic Zones

Climatic Zones & Conditions (ICH / WHO Guideline Basis)

Zone I – Temperate
- Long-term condition: 21 °C ± 2 °C / 45% RH ± 5%
- Countries: Northern Europe, Canada, UK, Russia (temperate parts).
- Frequency: Long-term (12 months+), accelerated (40 °C/75% RH for 6 months).
Zone II – Subtropical / Mediterranean
- Long-term condition: 25 °C ± 2 °C / 60% RH ± 5%
- Countries: Most of Europe (Italy, Spain, France, Germany), USA, Japan, Australia, New Zealand.
- Frequency: Long-term (12–24 months), accelerated as per ICH Q1A.
Zone III – Hot & Dry
- Long-term condition: 30 °C ± 2 °C / 35% RH ± 5%
- Countries: Middle East (Saudi Arabia, UAE, Kuwait), parts of Mexico, Argentina.
- Frequency: Long-term (12–24 months), accelerated (40 °C/75% RH for 6 months).
Zone IVa – Hot & Humid
- Long-term condition: 30 °C ± 2 °C / 65% RH ± 5%
- Countries: India, China (South), Brazil, Thailand, much of Africa (Kenya, Tanzania, Nigeria).
- Frequency: Long-term (12–24 months), accelerated (40 °C/75% RH for 6 months).
Zone IVb – Hot & Very Humid (WHO extension)
- Long-term condition: 30 °C ± 2 °C / 75% RH ± 5%
- Countries: ASEAN countries (Indonesia, Philippines, Vietnam, Malaysia), Bangladesh, Central Africa (Congo, Ghana).
- Frequency: Long-term (12–24 months), accelerated (40 °C/75% RH for 6 months).

Long-term:
- 0, 3, 6, 9, 12 months (then every 6 months up to 24 months, then yearly till shelf life).
Accelerated (40 °C / 75% RH):
- 0, 3, 6 months.
Intermediate (if needed, e.g., Zone II failures at accelerated):
- 30 °C / 65% RH, 0–6 months.