The present legal situation regarding cleanness of ventilation systems

Regulation of the Minister of Internal Affairs and Administration of 16.08.1999 concerning the technical conditions of use of residential buildings (Journal U. 74/99) defines the technical conditions for use of residential buildings, together with the associated engineering installations and equipment, which shall be referred to as "buildings" in the Regulation (§1).
§13.1. Neither the conditions and method of using technical fixtures and installations nor the products used in their repair or maintenance may cause deterioration of the functional properties of the product supplied using such equipment and installations.
§22.1. Ventilation systems and fixtures should, during the period of their useful lives, ensure effective air exchange in rooms, as per the design assumptions.
§22.2. Ventilation systems and fixtures should, during the period of their useful lives, be maintained in a service condition guaranteeing their effective and reliable performance.
§23. The following should be provided during the lives of ventilation systems and fixtures:
1) ducts and fixtures being fully passable and tight,
2) maintaining full required section of grilles,
3) execution of necessary maintenance and renovation works,
4) implementation of post-audit recommendations issued by authorised regulatory authorities,
5) when necessary - evaluation of the technical condition of ventilation systems and fixtures.

Building Law (Journal of Laws of 2000, No. 106, item 1126), regulates the aspects of designing, building, maintenance and demolishing of building establishments and sets out the rules of proceeding for public administration authorities in these fields.
The Building Law states, inter alia, that:
Article 62.1 Buildings and other civil structures should be subject to the following actions taken by their owner or manager during their useful life:

1) regular inspection, at least once a year, consisting of checking the technical adequacy of:
a. elements of buildings, civil structures and systems exposed to harmful weather impacts and damaging effects of factors occurring during the life of the building,
b. environmental protection systems and plant,
c. gas systems and chimney flues (smoke, flue gas and ventilation ducts),

2) regular inspection, at least once every 5 years, consisting of checking the service condition and functional quality of the entire building or structure, the appearance of the facility and its surroundings (...).
A building establishment means (Article 3.1.):
a) a building with installations and technical facilities,
b) a civil engineering structure constituting a technical and functional whole, with installations and technical facilities,
c) a hardscape establishment.

Chapter VI of Regulation of the Minister of Infrastructure of 12.04.2001 on technical conditions for buildings and their locations (Journal of Laws No. 75 of 15.06.2002, item 690) [26] states that:
§147(1) Ventilation and air conditioning should ensure proper quality of the indoor environment, including air exchange size, purity, temperature, relative humidity, movement rate in the room, in accordance with other applicable regulations and requirements of the Polish Standards concerning ventilation, as well as fire safety requirements and acoustic requirements prescribed in the Regulation.
§153(6): Ducts should be fitted with inspection openings, allowing for cleaning their interior as well as other fixtures and system elements unless cleaning is possible in the given design otherwise than through these openings, save that such openings shall not be located in rooms with elevated hygiene requirements.
§154(3): Mechanical ventilation and air conditioning equipment, such as air handling units, fan coil units, air conditioning units, heating and cooling-ventilation devices should be installed so as to enable their periodical inspection, maintenance, repair or replacement.
§154(5): For rooms with special hygiene requirements, the applied ventilation and air conditioning AHUs should enable compliance with improved purity standards inside the housing and should be fitted with internal lighting and sight glasses for verifying the condition of the unit from outside.
§154(6): Mechanical ventilation and air conditioning units should be secured from contaminants in ambient air, and in special cases of circulation (recirculation) air - with filters:
1) heating, cooling devices and heat recovery units - at least to G4 class,
2) humidifiers - at least to F6 class as specified in the Polish Standard concerning air filters classification.

Chapter 7 "Technical installations and fixtures": Regulation of the Minister of Internal Affairs and Administration of 16 June 2003, concerning fire protection of buildings, other civil structures and sites (Journal of Laws 2003 No. 121, item 1138) [13] states that:
§ 30.2. Contaminants from ventilation ducts such establishments as referred to in section 1 shall be removed at least once a year, unless a higher frequency is required on the basis of the functional conditions.
Section 1 enumerates establishments where solid, liquid or gaseous fuel burning process is implemented, including collective food service and catering service establishments.