Niklas Vartiainen, Geological Survey of Finland, PO Box 96, FI-02151 Espoo, Finland; niklas.vartiainen(at)gtk.fi
The statutory requirements placed on mine closure in Finland derive from a set of various statutes governing inter alia mining activity, environmental protection and waste management. Some statutes are applied to all mining projects by default (for example the Mining Act (621/2011) and the Environmental Protection Act (86/2000)) and others are applied to the activity in question based on the scale, nature and/or location of the activities.
The wide scope of legislation applicable to mining operations is exemplified in Section 3 of the Mining Act. Accordingly, provisions laid down in the Mining Act, decisions on mining permit and mining safety permit issues and other activities must comply with inter alia the provisions of the Conservation Act (1096/1996), the Environmental Protection Act, the Act on the Protection of Wilderness Reserves (62/1991), the Land Use and Building Act (132/1999), the Water Act (264/1961), the Reindeer Husbandry Act (848/1990), the Radiation Act (592/1991), the Nuclear Energy Act (990/1987), the Antiquities Act (295/1963), the Off-Road Traffic Act (1710/1995) and the Dam Safety Act (494/2009). The list is incomprehensive. The Mining Act does not itself supersede other statutes but rather is to be applied in compliance with other acts.
Due to the fact that every mining project has its own special characteristics the applicable legislation to a said mining project needs to be determined on a case by case basis, examining whether the activity in question falls within the scope of a certain statute. It is therefore inevitable that the applicable legislation and stipulations for mine closure can vary from project to project.
Requirements regarding mine closure are stipulated at mainly in two layers: on a legislation level and on the other hand through various government issued permits, which must be obtained prior commencing mining operations. These permits include inter alia the mining permit and mining safety permit issued in accordance of the Mining Act, the environmental permit issued under the Environmental Protection Act and the water permit issued under the Water Act. All orders and regulations given by the authorities are assessed and issued on a case by case basis. The orders and regulations issued through the different permits can therefore vary from permit to permit.
In addition, mining activity is also regulated through a number of guides and instructions given and published by various authorities, experts and scientists.
Sources of statutory requirements for mine closure
The Mining Act
The principal statute governing mining activity in Finland is the Mining Act, which came into force 1 July 2011, repealing the 1965 Mining Act. The Mining Act contains provisions governing, inter alia, the exploration and exploitation of mining minerals and proceedings establishing a mining area in Finland.
A number of provisions governing mine closure can be found from the Mining Act ranging from provisions regarding time limits for measures to be preformed to provisions regarding the removal of mining equipment from the mining site. It should be noted that although the terms after-care and rehabilitation might refer to measures performed after the termination of mining operations, the Mining Act obligates the mining operator to take into consideration mine closure already in the planning stages of the mining project. This requirement of consideration penetrates the whole mining project so that in every stage of the mining project the mining operator is required by the Mining Act to have up to date plans regarding mine closure and measures related to mine closure (see Closure Actions Plans).
In order for this presentation to flow in a chronological order, the permits required under the Mining Act will be examined next and then the statutory requirements regarding the termination of mining activities laid down in the Mining Act will be studied. Also collateral required under the Mining Act will be introduced.
Mining activity in Finland is subject to a mining permit. A mining permit is required for the establishment of a mine and the undertaking of mining activity. The mining permit issues are in most cases decided by the mining authority, which according to Section 4 of the Mining Act is the Finnish Safety and Chemicals Agency (Tukes).
The mining operator is required to take into consideration the termination of mining activities already in the planning stages of the mining project. This requirement can be found in two Sections in the Mining Act; Sections 120 and 34.
According to Section 120 of the Mining Act the mining operator must take into consideration the safe termination of mining activity at every stage of the mining project. According to the Government Proposal for Mining Act (HE 273/2009 vp, hereafter “the Government Proposal”), the termination of mining activity and the closing of the mine should be conducted in a planned manner. The most efficient and convenient way to satisfy this requirement is to take into consideration the safe closing of the mine already when planning and constructing the mine.
The requirements regarding the content of a mining permit application are laid down in the Mining Act and in Section 16 of the Government Decree on Mining Activities (391/2012).
The mining application must include inter alia a reliable report regarding the termination of activities and related measures, alongside after-care measures to be performed once the mining activity is terminated.
The Government Decree on Mining Activities further stipulates, that the report mentioned above must contain inter alia:
- A report on the measures required by the termination of mining activities and their regional scope.
- A report on the measures related to buildings and constructions after the termination of mining activities.
- A report on the objectives and primary content of mine closure measures.
- A report on the options available for the area’s future use.
- An estimate of the schedule and costs of termination measures.
The reports regarding the termination of mining activities provided to the mining authority in the application stage requires the mining operator to take into consideration inter alia the requirements laid down in Section 143 of the Mining Act. The mentioned requirements are examined in the latter part of this presentation. (According to the Section 143 of the Mining Act the mining operator is obliged to restore the mining area to a condition complying with public safety. The mining operator must also ensure the restoration, cleaning and landscaping of the mining area.)
Orders and regulations contained in mining permits
Laying down specific regulations and orders regarding the mining activity is part of the permit consideration carried out by the mining authority. Section 52 of the Mining Act stipulates the scope and contents of the orders that the mining authority is required to include in the mining permit. Accordingly, orders regarding inter alia mine-closure alongside other obligations related to termination of mining activities and those after termination are to be included in a mining permit.
Orders regarding mine closure imposed on mining operators through mining permits or decisions issued to mining right holders (see chapter “Mining operations based on the Repealed Mining Act”) are according to the prevailing practice general in nature and do not contain detailed orders regarding measures to be performed once the operations are terminated. In most cases orders regarding the termination of mining activities state the following or similar:
“The mining permit holder is obliged to ensure that mining activities do not cause damage to people’s health or danger to public safety”
“The mining permit holder is obliged to ensure that mining activities do not cause significant harm to public or private interests or infringement of public or private interests.”
Mining Safety Permit
In addition to a mining permit, mining activity is subject to another permit issued under the Mining Act by the mining authority; the mining operator must obtain a mining safety permit prior commencing mining activities.
One of the prerequisites of issuing a mining safety permit is that the mining operator has taken Section 120 of the Mining Act into consideration in the planning stage of the mine and mining activities.
The mining authority is obliged to issue orders regarding safety through the mining safety permit and according to the Mining Act the mining safety permit must contain inter alia orders for securing public and private interests concerning termination of mining activity.
Orders contained in mining safety permits
The orders found in mining safety permits are general in nature and do not stipulate in detail the measures to be performed once mining operations are terminated.
Currently the requirement laid down in Section 125 of the Mining Act (mining safety permit must contain orders for securing public and private interests concerning termination of mining activity) is satisfied by the following type of orders:
“The mining operator shall take into consideration, during the planning, construction and in operation that the mining activity can be terminated and the mine closed in a safe manner.”
“The mining operator shall take into consideration, during the planning, construction and in operation that the mining activity can be terminated and the mine closed in a safe manner. The operator has provided that the termination of the mine is taken into consideration in the after-care plan, performed together with best available practices. The mining authority shall assess the functionality of the plan and possible need of update of the plan alongside the periodic inspection of the mine.”
Termination of Mining Activities under the Mining Act
The provisions regarding the termination of mining activities found in the Mining Act are general in nature and no provisions containing detailed stipulation on measures necessary to perform in order to ensure the restoration of the mining site can be found.
Section 143 of the Mining Act lays down the required measures regarding the restoration of the mining area. Accordingly the mining operator must:
- Restore the mining area to a condition complying with public safety and
- Ensure the restoration, cleaning and landscaping of the areas.
- Carry out measures specified in the mining permit and mining safety permit
According to Section 144 of the Mining Act the mining operator may leave in place the mining minerals excavated from the mine, and the buildings and other constructions on the ground for up to two years after termination of mining activity. Thereafter, they shall be transferred, free of charge, to the landowner, who may demand their removal at the operator’s cost.
After completing the measures and obligations stipulated in Sections 143 and 144 of the Mining Act the mining operator shall submit notification to the mining authority which should include inter alia an account of the measures performed.
After receiving the notification of the after-care measures performed from the mining operator the mining authority shall arrange a final inspection of the mining site.
The mining authority determines through the final inspection process whether measures and obligations referred in Sections 143 and 144 of the Mining Act have been properly completed and fulfilled. The final inspection is concluded by a decision to terminate mining activity. The decision includes orders necessary in terms of public and private interests concerning completion of termination measures within the given time limit, monitoring of the mining area and auxiliary area to the mine, buildings and other constructions located in the mining site and other elements whose consideration is necessary in terms of protecting public and private interests.
After the termination of the mining activity, the mining operator remains responsible for monitoring the mining area in compliance with the orders issued in the mining permit or those in the decision to terminate mining activity alongside the necessary corrective measures and the costs incurred therein. The mining operator is also obliged to notify the mining authority of all significant detrimental impacts on public safety detected during monitoring and implementing the necessary corrective measures.
The Section mentioned above gives the mining authority the right to issue orders regarding necessary corrective measures.
Collateral under the Mining Act
The mining operator is subject to several financial guarantees to ensure the appropriate execution of after-care measures which the mining operator is obliged to fulfil. For the sake of clarification, collateral set in accordance with the Mining Act will hereafter be referred to as “mining collateral” and collateral set in accordance with the Environmental Protection Act will hereafter be referred to as “waste collateral”.
To ensure that after-care measures are appropriately performed in situations where the mining operator cannot itself fulfil the measures laid down in the Mining Act, the mining permit or mining safety permit, the Mining Act contains provisions regarding the deposit of mining collateral. The deposit is intended to cover the actual costs flowing from the performance of the measures mentioned above.
It should be noted, that mining collateral is not intended to cover costs arising from the restoration measures required to be performed by another statute. Mining collateral only covers measures required to be performed under the Mining Act. These measures mostly relate to the ensuring of public safety, safety of the mining site and removal or securing of various constructions found in the mining site. Collaterals issued under different acts are intended only to supplement each other and not to overlap.
A mining permit must include an order concerning mining collateral and the type and quantity of mining collateral is determined by the mining authority. The quantity of mining collateral should be sufficient in view of the nature and extent of mining activity, the permit regulations issued for the activity and collateral demanded by virtue of other legislation. The deposit of mining collateral is one of the prerequisites for commencing mining operations.
At the moment no official guidelines have been set by the mining authority regarding the estimation of costs arising from the measures required to be performed after the termination of mining activity.
Should the detrimental impacts of the activities deviate substantially from the assessments made during permit consideration; the mining authority can revise the quantity of mining collateral on its own initiative. It should be stressed that this is possible only if the impact of the activities deviate from the assessments made during the permit consideration.
Orders regarding mining collateral
Orders and the amounts regarding mining collateral vary, depending on the nature and scale of the activities in questions. The amounts of mining collateral range from e.g. collateral issued to Suurikuusikko Mine 1,568,700 EUR to the Lehlampi Mine collateral of 9,000 EUR. In certain cases the mining authority has not ordered collateral to be deposited, if the mining operations have not been commenced.
According to the decisions made by the mining authority, mining collateral is intended to cover e.g. the following measures:
- Removal of unnecessary structures, chemicals, explosives, electrical equipment, machinery and wastes, gentling and shaping of the slopes, blocking of the drive to the open pit, blocking of the access to the tunnel and shafts, fencing, demolishment of the unnecessary roads
- Removal of buildings, electrical lines, water reservoir pool, pumping stations and pipelines
- Restoration of open pit and underground mine.
- Rehabilitation of the landfill area
- Securing the pilot plant and the mining site
- Gentling of the slopes
- Fencing and securing the open pit, warning sings
Mining Operations based on the Repealed Mining Act
Most mining operations in Finland are based on mining concessions issued under the repealed Mining Act (hereafter referred to as “the Repealed Act”). According to Section 181 of the Mining Act these mining concessions remain valid under the terms specified in the decision regarding the issuing of the mining concession decision. Correspondingly, most of the provisions laid down in the Mining Act governing mining activities shall further apply to activity undertaken under a mining right. Consequently, the aftercare provisions laid down in chapter 15 of the Mining Act apply also to mining activities which are based on mining rights issued under the repealed Mining Act.
Within three years from the issuing of the Mining Act, the mining authority was obliged to issue mining right holders with orders necessary as regards public and private interests, in compliance with Sections 52 and 125 of the Mining Act. Section 52 stipulates the type of orders which are to be included in a mining permit and Section 125 stipulates the type of orders which are to be included in a mining safety permit.
In addition, the mining authority was obliged to issue orders regarding collateral for the mining right holders.
While the mining right holders are not obliged to apply for a mining safety permit, the mining right holder are however obliged to report to the mining authority how mining safety regulations laid down in the Mining Act and in the Government Decree on Mining Safety have been taken into consideration. The report mentioned above must contain inter alia a declaration on how mine closure has been taken into account in the planning, construction and operation of the mine.
Environmental Protection Act and the Government Decree on Extractive Waste
Activities that pose a threat of environmental pollution are subject to an environmental permit issued under the Environmental Protection Act. Certain activities by definition require an environmental permit such as mining activity and waste site for extract waste. Waste sites for extract waste are further governed by the Government Decree on Extractive Waste (Valtioneuvoston asetus kaivannaisjätteistä 379/2008).
The environmental permit must contain orders regarding inter alia measures to be performed after the termination of operations, such as remediation of the area and prevention of emissions and other measures to prevent, reduce or assess pollution, the risk thereof and adverse effects caused by it. Necessary regulations on the operative monitoring of the activity and on the monitoring of emissions, the impact of the activity and the monitoring of the state of the environment following the cessation of the activity must also be issued as part of the environmental permit.
Further, orders regarding inter alia the termination of a waste site for extract waste must be included if applicable. An environmental permit regarding mining activity must also inter alia contain:
- a waste management plan for extractive waste
- conditions governing compliance with the plan. 
The Government Decree on Extractive Waste lays down the requirements regarding the contents of a waste management plan. Accordingly, the waste management plan must contain a proposed plan for closure, including rehabilitation, after-closure procedures and monitoring.
A waste site for extractive waste shall be considered terminated when the environmental authority has performed a final inspection on the site and has found the after-care measures appropriately completed, so that the waste site and its impact area have been restored into a satisfactory state and the orders and regulations given in the environmental permit have been followed as issued in the permit.
The operator remains responsible for the restoration measures as long as necessary to ensure that the site does not cause threat to the environment, the site is stabile and permanently rehabilitated, the site does not impose danger and control of the environmental impacts is no longer needed.
Measures required to be performed on the site are stipulated in the environmental permit or in a permit issued under Section 90 of the Environmental Protection Act, which enables the environmental authority to issue orders regarding the prevention of pollution and monitoring of the effects of the activities after termination of mining operations.
Orders for mine closure found in environmental permits
The environmental permits are considered and decided always on a case by case basis and the orders regarding the rehabilitation measures and provisions regarding mine closure may differ from project to project.
Orders found in environmental permits usually relate to
- measures regarding the permanent removal of mining equipment, machinery, chemicals, fuels and waste which might cause pollution from the mining site
- measures to ensure that the area is brought to a state satisfying the requirement of public safety
- measures to ensure the adequate surface structures of (extractive) waste sites
- measures regarding the rehabilitation and landscaping
- measures regarding the monitoring of the site
In certain cases a separate closure plan is required to be prepared. This type of permit order is usually implemented so, that the operator is required to draw up a closure plan and obtain an approval from the relevant authorities for the plan. Approval of the plan must be obtained prior the termination of activities.
Collaterals under the Environmental Protection Act and the Government Decree on Extractive Waste
The Environmental Protection Act and the Government Decree on Extractive Waste govern collaterals set to cover costs arising from the restoration measures regarding waste sites and waste sites for extractive waste. These collaterals are ordered by the State Regional Administrative Agency through the environmental permit. Depositing collateral ordered in the environmental permits is a prerequisite for commencing operations and/or before extractive waste can be dumped on the site.
Collateral issued in an environmental permit ensures that waste treatment and rehabilitation measures are appropriately performed in case the operator fails to carry out the said measures. The measures covered by the collateral issued in environmental permit include waste management, supervision, and measures required for terminating operations and measures performed after the termination.
In order for the collateral to be effective so that performance of the aftercare measures can be ensured, the quantity of collateral issued must be sufficient. The extent and nature of, and regulations issued regarding the activity in question must be taken into consideration. To ensure the appropriate quantity of collateral regarding landfill and other long-term operations, the environmental permit must ensure that collateral accrues over time to correspond, as well as possible, to the cost of terminating the operations at the time of assessment. In practice this provision is enforced by binding the quantity of the financial guarantee on the acreage of the waste site. 
Regarding waste sites for extractive waste, the restoration measures are defined in more detail in the extractive waste management plan. Collateral for a waste area for extractive waste must also cover the costs of restoring a land area located within the area of impact of the waste area to a satisfactory state.
Other legislation applicable to mine closure
Water resource management projects are subject to a permit if they may cause changes in the state, depth, water level or flow, shore, or aquatic environment of a water body or the quality or quantity of groundwater. The water permit issue is decided together with the environmental permit, if the same project requires both a water permit and an environmental permit.
Typical activities falling within the scope of the water act during the course of a mining project are water abstraction and regulation of watercourse.
The water permit shall include orders and regulations regarding inter alia landscaping and other elimination of traces of work and measures and devices necessary to preserving the state of the water body and groundwater body.
Chemical Safety Act
When a production facility using chemicals is closed down, the operator must ensure that the structures and the production facility are cleaned and chemicals or explosives do not cause damage to people, property of the environment.
Act on Environmental Impact Assessment Procedure
The aim of the Act on Environmental Impact Assessment Procedure is to further the assessment of environmental impact and consistent consideration of this impact in planning and decision-making, and, at the same time, to increase the information available to citizens and their opportunities to participate.
The assessment procedure is applied to the extraction, dressing and processing of metal ores and other mined minerals when the total amount of the extracted material is at least 550,000 tonnes per year, or quarries and opencast mines with a surface area larger than 25 hectares.
If the project falls within the scope of the Act on Environmental Impact Assessment Procedure the environmental impacts of a project must be assessed in accordance with the assessment procedure before any action relevant in terms of environmental impact is taken to implement the project.
The aim is to study the different options of the proposed project and to determine the environmental impacts of the different options. This naturally includes the assessment of different options related to mine closure and measures to be carried out once the operation is terminated.
The assessment procedure starts with the operator submitting the assessment programme to the coordinating authority at the earliest possible stage of planning.
The coordinating authority then announces the assessment programme and accepts the opinions made by the public. The coordinating authority then delivers its own statement and other statements and opinions to the developer.
Next, the developer assesses the impacts of the project and its various alternatives on the basis of the assessment programme and the coordinating authority’s statement, and prepares an environmental impact assessment report.
Once the assessment report has been submitted to the coordinating authority, the report is announced and the opinions of the public are accepted.The assessment procedure is concluded when the coordinating authority delivers its statement and other statements and opinions to the operator. The statement is also submitted for information purposes to authorities dealing with the project, to the municipalities within the area of impact of the project and, as necessary, to regional councils and other appropriate authorities.
An authority may not grant a permit for implementation of a project before it has obtained an assessment report and the coordinating authority’s statement on it.
Further, a permit decision on a project shall state in what way the assessment report and the coordinating authority’s statement on it have been taken into account.
Contaminated soil treatment and compensation
The Environmental Protection Act prohibits soil contamination. Accordingly waste or other substances, or organisms or micro-organisms shall not be dumped or discharged on the ground or in the soil so as to result in such deterioration of soil quality as may endanger or cause harm to health or the environment, substantially impair the amenity of the site or cause comparable violation of the public or private good. Similar prohibition to pollute groundwater can be found in Section 8 of the Environmental Protection Act.
According to Section 75 of the Environmental Protection Act party whose activities have caused the contamination of soil or groundwater is required to restore said soil or groundwater. According to Section 76 of the Environmental Protection Act the polluter shall notify the supervisory authority immediately.
The Centre for Economic Development, Transport and the Environment is entitled to order remediation of the contaminated soil or groundwater if the party responsible for treatment does not take action. When assessing the need for the remediation, the Centre for Economic Development, Transport and the Environment must take into account the present and future use of the contaminated area, its surroundings and the groundwater, and any danger or harm to the environment and health that would be caused by the contamination.
According to Section 105 of the Mining Act damage or inconvenience caused by pollution of water, air, or soil, or by noise, vibration, radiation, light, heat, smell, or similar nuisance, the provisions laid down in section 12 of the Act on Compensation for Environmental Damage (737/1994) shall apply.
According to Section 1 of the Act on Compensation for Environmental Damage compensation must be paid for a loss resulting from:
1) pollution of the water, air or soil;
2) noise, vibration, radiation, light, heat or smell; or
3) other similar nuisance.
Liability to compensate arises if
- causal link between the activities and the loss is shown.
- toleration of the nuisance is deemed unreasonable. The obligation to tolerate the nuisance shall not, however, apply to loss inflicted deliberately or criminally, nor to bodily injury, nor to material loss of greater than minor significance.
Even when the loss has not been caused deliberately or negligently, liability for compensation shall lie with a person
1) whose activity has caused the environmental damage;
2) who is comparable to the person carrying out the activity, as referred to in subparagraph 1; and
3) to whom the activity which caused the environmental damage has been assigned, if the assignee knew or should have known, at the time of the assignment, about the loss or the nuisance referred to in section 1 or the threat of the same.
 Section 16 of the Mining Act
 Section 33 of the Mining Act
 Section 34 of the Mining Act
 Section 34 of the Mining Act
 Section 16 of the Government Decree on Mining Activities
 See e.g. Decisions Tukes, 24.6.2014, KaivNro 2299, 2354, Kvartsila Mine (http://www.tukes.fi/Tiedostot/Kaivospiirit/Yleiset_yksityiset_paatokset/20_Kinahmi%20ja%20Kvartsila.pdf, in Finnish) and Tukes, 26.8.2014, KaivNro K20141, KL2013:0005, Kuusela-Kalkkila Mine (http://www.tukes.fi/Tiedostot/Kaivospiirit/KUUSELA-KALKKILA%20p%C3%A4%C3%A4t%C3%B6snetti.pdf, in Finnish)
 Section 121 of the Mining Act
 Section 120 of the Mining Act requires the mining operator to take into consideration the safe termination of mining activity at every stage of the mining project.
 Section 124 of the Mining Act
 Section 125 of the Mining Act
 Pahtavaara Mine, Mining Safety Permit 15.1.2014, 8579/35/2013
 Tipas Mine, Mining Safety Permit, 15.1.2014, 8826/35/2013
 Section 145 of the Mining Act
 Section 146 of the Mining Act
 Section 146 of the Mining Act
 Section 147 of the Mining Act
 Section 148 of the Mining Act
 Section 150 of the Mining Act
 Section 110 of the Mining Act
 Separate collateral to be set for the costs regarding measures related to the restoration of the environment is required under the Environmental Protection Act which is set to ensure proper waste management. This collateral covers costs related to the restoration measures performed on tailings ponds, waste-rock dumps and to similar waste sites. An order regarding this collateral can be found in the environmental permit.
 Section 110 of the Mining Act
 Section 52 of the Mining Act
 Section 109 of the Mining Act
 Section 108 of the Mining Act
 Section 168 of the Mining Act
 Section 109 of the Mining Act
 Section 21 of the Government Decree on Mining Safety
 Section 28 of the Environmental Protection Act
 Government Decree on Environmental Protection
 Section 43 of the Environmental Protection Act
 Section 46 of the Environmental Protection Act
 Section 14 the Government Decree on Extractive Waste
 Section 45 a of the Environmental Protection Act
 Section 14 of the Government Decree on Extractive Waste
 Section 43 a of the Environmental Protection Act
 Section 43 c of the Environmental Protection Act
 Government Decree on Extractive Waste
 Chapter 3 Section 2 of the Water Act
 Chapter 3 Section 10 of the Water Act
 Section 133 of the Chemical Safety Act (Laki vaarallisten kemikaalien ja räjähteiden käsittelyn turvallisuudesta 390/2005)
 Section 1 of the Act on Environmental Impact Assessment Procedure
 Section 6 of the Decree on Environmental Impact Assessment Procedure
 Secion 7 of the Act on Environmental Impact Assessment Procedure
 Secion 8 of the Act on Environmental Impact Assessment Procedure
 Secions 8 a and 9 of the Act on Environmental Impact Assessment Procedure
 Secion 10 of the Act on Environmental Impact Assessment Procedure
 Secion 11 of the Act on Environmental Impact Assessment Procedure
 Section 12 of the Act on Environmental Impact Assessment Procedure
 Section 13 of the Act on Environmental Impact Assessment Procedure
 Section 7 of the Environmental Protection Act
 Section 79 of the Environmental Protection Act
 Section 77 of the Environmental Protection Act
 Section 3 of the Act on Compensation for Environmental Damage
 Section 4 of the Act on Compensation for Environmental Damage
 Section 7 of the Act on Compensation for Environmental Damage