There are some activities that could be carried out in Environmental Science or Geography that do have some chemical hazards.
For instance some analytical procedures for looking at substances in water or soil can involve the use of chemicals that are toxic or harmful in other ways. Very few are high hazard but it is important to be aware of any risks.
Others may produce harmful fumes - for instance demonstrations of acid rain can produce toxic sulphur dioxide or nitrogen dioxide.
Work with soils and the like can produce dusts and inhalation of these, even if there is no specific hazard, should be avoided.
Working with sol and compost - as well as any other biological substance - can expose learners and others to fungal or bacertial spores so suitable precautios should be taken.
Fieldwork of all sorts involves a range of risks, which will vary with the location and the activities involved.
Below we have a range of model risk assessments that can be adapted vor any of your activities.