On 28 August 2020 the Ministry of Health published the following projects on the National Regulatory Improvement Commission's (CONAMER's) online system for consultation:
- Mexican Official Standard PROY-NOM-025-SSA1-2020, Environmental Health, Criteria for Evaluating the Quality of Ambient Air with Respect to Suspended Particles PM10 and PM5 (PROY-NOM-025); and
- Mexican Official Standard PROY-NOM-020-SSA1-2020, Environmental Health, Criteria for Evaluating Air Quality with Respect to Ozone Values (PROY-NOM-020).
Each project proposes to introduce new goals and standards for air quality in Mexico through a five-year implementation plan that would see a gradual reduction of the concentration of particles and ozone in the environment.
The existing standards for particles and ozone form the basis of the environmental contingency programmes that various Mexican states have implemented in recent years. These contingency programmes are designed to limit certain activities when elevated concentrations of particles or ozone are identified in the environment, including:
- restricted vehicle circulation;
- reduced operating hours for industrial sites; and
- the shutdown of certain processes.
Thus, the standards set out under PROY-NOM-025 and PROY-NOM-020 for industrial sectors are important.
The relevant aspects of both projects can be summarised as follows (all standards are expressed in µg/m3).
The current standard for particles of PM10 is a concentration of 75 for a 24-hour period and a yearly concentration limit of 75. For PM5, the current standard is a concentration of 45 for a 34-hour period and a yearly concentration limit of 12.
PROY-NOM-025 proposes a starting concentration limit for PM10 of 70 for a 24-hour period and a yearly concentration limit of 36, with a final concentration limit (after five years) of 50 for a 24-hour period and a yearly concentration limit of 20. For PM5, it proposes a starting concentration limit of 41 for a 24-hour period and a yearly concentration limit of 10, with final limits of 25 for a 24-hour period and a yearly concentration limit of 10.
The current standard for ozone concentration is an hourly concentration limit of 185 and an eight-hour concentration limit of 136.
PROY-NOM-020 proposes a starting hourly concentration limit of 176 and an eight-hour concentration limit of 127, with a final hourly concentration limit of 176 and a final eight-hour concentration limit of 100 after five years.
The first-year concentration limits for both projects would be enforceable as of the date of publication of the updated Mexican Official Standards in the Federal Official Gazette. Such limits would apply for one calendar year.
Testing methods will remain the same as those currently accepted and used.
While PROY-NOM-025 and PROY-NOM-020, as well as the current standards, apply to government authorities, they serve as the basis for other types of regulation and standard which apply to the private sector – in particular, those that could form the basis of measures and other regulatory requirements to tackle and reduce air pollution caused by different fixed and mobile sources. These include the aforementioned contingency programmes, as well as Mexican Official Standard NOM-085-SEMARNAT-2011, which sets out maximum permissible levels of various pollutants, including particles, for industrial activities which involve combustion processes.
These proposed stricter standards will likely result in the revision of air emission and air quality-related standards and obligations, as industrial operations are a large contributor of ozone and particle emissions in the environment; thus, private sector entities should pay close attention to both projects as they could result in the application of additional internal measures or the use of equipment and other sources to meet the stricter pollutant thresholds.
Under the General Regulatory Improvement Law, projects regarding Mexican Official Standards are subject to a public consultation process. As such, interested parties can submit comments on both proposed standards to the corresponding authority via CONAMER's online system.
