Mexico: Air Quality Standards

Overview

The current Air Quality Mexican Official Standards defined by the Secretary of Health, regulate 7 criteria pollutants by setting maximum allowable concentrations. They were implemented in 1994 but some of them have been updated in recent years. Mexico’s Ecology and Climate Change Institute (INECC) also monitors nationwide air quality to allow for more effective enforcement.

Standard type
Ambient air quality standard

Regulating Body
Secretaría de Salud, Secretary of Health

Applicability
Nationwide

History

Air quality legislation has been in place in Mexico since the 1970s, and current ambient air quality at the federal level is regulated by Mexico’s Secretary of Health, Secretaría de Salud. In 1994, the Secretaria de Salud issued a series of Mexican official standards, or normas oficiales (NOMs), that regulate maximum concentrations of environmental contaminants. These include 7 criteria pollutants: carbon monoxide (CO), ozone (O3), nitrogen dioxide (NO2), particulate matter (PM2.5 and PM10), sulfur dioxide (SO2) and lead (Pb). Standards for ozone and particulate matter were updated in 2014.

Mexico’s Ecology and Climate Change Institute, Instituto Nacional de Ecologia y Cambio Climatico (INECC), which functions as the research arm of The Secretary of Environment, Secretaría del Medio Ambiente y Recursos Naturales (SEMARNAT), monitors air quality and manages the Air Quality National Information System (SINAICA).

Technical Standards

Carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), particulate pollution (PM2.5 and PM10), and sulfur dioxide (SO2) are the criteria pollutants regulated in Mexico.

Current limit values are presented in the following table.

Pollutant[final rule cite] Standard Averaging Time Form
Ozone[NOM-020-SSA1-2014] 0.095 ppm 1-hour Not to be exceeded over a period of one year
0.070 ppm 8-hour 75th percentile, over a period of one year
Carbon Monoxide[NOM-021-SSA1-1993] 11.00 ppm 8-hour Not to be exceeded more than once per year
Sulfur Dioxide[NOM-022-SSA1-1993] 0.110 ppm 24-hour Not to be exceeded more than once per year
0.025 ppm Annual Not to be exceeded
Nitrogen Dioxide[NOM-023-SSA1-1993] 0.210 ppm 1-hour Not to be exceeded more than once per year
Particle Pollution[NOM-025-SSA1-2014]
PM10 75 μg/m3 24-hour 75th percentile of each hour concentration per day, averaged over a period of one year
40 μg/m3 Annual 75th percentile of each 24-hour concentration per trimester, averaged over one year (at least 3 trimesters)
PM2.5 45 μg/m3 24-hour 75th percentile of each hour concentration per day, averaged over a period of one year
12 μg/m3 Annual 75th percentile of each 24-hour concentration per trimester, averaged over one year (at least 3 trimesters)
Lead[NOM-026-SSA1-1993] 1.5 μg/m3 3 months Not to be exceeded

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