alkaline
artificial
ash
carcinogenic
cement
danger
dangerous
ecology
environment
estonia
european union
forest
green
harmful
hazardous
heap
hill
idaviru
industrial
industry
land
landmark
material
mineral
monument
natural
nature
oil shale
old
open
outdoors
pollutant
pollution
region
resources
risk
stone
territory
threat
topography
toxic
utilization
waste
white