Dust particles, airborne, San Miguel de Allende (C) Daniel Friedman Air Quality Study, San Miguel de Allende, Mexico

  • AIR QUALITY STUDY San Miguel de Allende - CONTENTS: What particles are found in outdoor air in a colonial city at 6500 ft. in central Mexico. Beginning in 2012 we are conducting an ongoing series of airborne particle studies reports on airborne dust levels, total particle counts, and biological particle counts in San Miguel de Allende in Guanajuato, Mexico
  • POST a QUESTION or READ FAQs about airborne dust contents, mold, pollen, allergens in Central Mexico
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Air quality & airborne dust particle analysis for San Miguel de Allende, Mexico:

This article describes an ongoing series of air quality studies that report on the nature of outdoor airborne particulates in San Miguel de Allende, located in Guanajuato, Mexico.

San Miguel de Allende is a colonial city of 140,000 located at about 6500 feet of altitude in the center of Mexico, about 274 kilometers north of Mexico City. Here we report on the results of air quality tests based on particle samples collected at different seasons and time of day and under varying weather conditions.

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What is in the Air in San Miguel de Allende? Airborne Particle Study

Stachybotrys spores (left) and structure (right)Daniel Friedman, Isabel Sanchez Luna

Here we provide tables of the contents of typical airborne dust sampled both outdoors and inside buildings in San Miguel de Allende, Guanajuato, Mexico. Using a Burkard personal air sampler (photo at left) allows high portability and airborne particle concentration sampling in a variety of locations and under varying conditions.

As additional samples are collected and analyzed in our local microscopy lab we will add to the data air quality information describing air samples collected during varying seasons, times of day, and weather conditions.

If our study observes particularly high levels of known or suspected airborne irritants such as common allergens, pollen, or mold (airborne fungal spores) we will note those conditions as well.

Notice: This is an independent, un-funded, private study whose results are shared with the public. These results are in no way "official" and cannot be taken as representative of air quality conditions other than for the specific date, time, and location where samples were collected. We welcome questions or suggestions about this material: please use the Q&A box found at the end of this article.

Air Sample Results for San Miguel de Allende, Guanajuato, Mexico

Sample Date, Time, Weather, Locale
Particle Type/ID

05 Jul 2012, 16:00 hrs.
Col. San Antonio, outdoors, 2nd fl, 16:00 hrs, sun, recent rain, wind < 10 kph.
Burkard PAS, 80L, KOH, 400x & 1000x, 100% of trace was counted for fungal spores & pollen

Summary: sample dominated by Cladosporium sp., Ascomycetes, and non-fungal mineral-dust particles. Soil particles including ultra-fines, high. Pollen count: low. Total particle count: low.



Aerobiological Particles Particles
M3 of air
Alternaria sp. 88          
Algae 13          
Amerospores 50          
Ascomycetes 350          
Basidiomycetes 13          
Cladosporium sp. 450          
Hyphal fragments 88          
Insect fecals 13          
Periconia sp. 13          
Pithomyces sp. 26          
Plant hairs fibers 13          
Pollen (sum) 38          
Unid. mitospores 38          
Total biologicals 1312          
Non-biological particles            
Fabric fibers 13          
Road dust/tire particles 38          
Road dust / mineral or soil particles
from 1u to 150u, adhered clusters counted as 1 particle
>50,000 estimated, <20% of trace counted         Note: bacterial or viral adherents to non-biological dust particles could be present but are not included in this analysis
Total non-biologicals >50,050          
Total particles
per M3 of air

Photographs of Airborne Particles From the Air Samples in the Table Above

Airborne dust & ascospores (C) Daniel Friedman Airborne spores (C) Daniel Friedman

5 Jul 2012, 4PM Col. San Antonio

Ascomycete cluster & soil particles (left);

smut spore cluster (right).

Research on Air Contaminants in San Miguel de Allende, Mexico: types of airborne pollutants

Some readers asked about testing San Miguel de Allende air for dioxins - not something that is considered in the aerobiological and dust characterization study (still in process) described above.

Dioxins and PCBs can be airborne contaminants as cited in the references below as may a great many other potential airborne pollutants arising from various business activities including fabrication, chemical and municipal waste burning (Czuczwa 1986).

Tire burning that has occurred around San Miguel de Allende and countless other cities around the world is a common source of heavy metal pollution.

  • Alcock, Ruth E., Peter A. Behnisch, Kevin C. Jones, and Hanspaul Hagenmaier. "Dioxin-like PCBs in the environment-human exposure and the significance of sources." Chemosphere 37, no. 8 (1998): 1457-1472.
  • Blackman, Allen, ed. Small Firms and the Environment in Developing Countries:" Collective Impacts, Collective Action". Routledge, 2010. [The bricks on the cover of this book are from San Miguel de Allende]
  • Booth, Shawn, Joe Hui, Zoraida Alojado, Vicky Lam, William Cheung, Dirk Zeller, Douw Steyn, and Daniel Pauly. "Global deposition of airborne dioxin."Marine pollution bulletin 75, no. 1 (2013): 182-186.
  • Czuczwa, Jean M., and Ronald A. Hites. "Airborne dioxins and dibenzofurans: sources and fates." Environmental science & technology 20, no. 2 (1986): 195-200.
  • Czuczwa, Jean M., and Ronald A. Hites. "Sources and fate of PCDD and PCDF." Chemosphere 15, no. 9 (1986): 1417-1420.
  • Fiedler, H., O. Hutzinger, and C. W. Timms. "Dioxins: sources of environmental load and human exposure." Toxicological & Environmental Chemistry 29, no. 3 (1990): 157-234.
  • Horner, Jonathan M. "Environmental health implications of heavy metal pollution from car tires." Reviews on environmental health 11, no. 4 (1996): 175-178.
  • Kulkarni, Prashant S., João G. Crespo, and Carlos AM Afonso. "Dioxins sources and current remediation technologies—a review." Environment international 34, no. 1 (2008): 139-153.
  • Kurokawa, Yoichi, Matsueda Takahiko, Nakamura Matayoshi, Takada Satoshi, and Fukamachi Kazumi. "Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans in various sizes of airborne particles." Chemosphere 37, no. 9 (1998): 2161-2171.
  • Mandal, Prabir K. "Dioxin: a review of its environmental effects and its aryl hydrocarbon receptor biology." Journal of Comparative Physiology B 175, no. 4 (2005): 221-230.
  • Mahlknecht, Jürgen, Ma Guadalupe Medina-Mejía, Jaime Gárfias-Solis, and Irene Cano-Aguilera. "Intrinsic aquifer vulnerability assessment: validation by environmental tracers in San Miguel de Allende, Mexico." Environmental geology 51, no. 3 (2006): 477-491.
  • Mercado‐Silva, Norman, John Lyons, Edmundo Díaz‐Pardo, Altagracia Gutiérrez‐Hernández, Claudia Patricia Ornelas‐García, Carlos Pedraza‐Lara, and M. Zanden. "Long‐term changes in the fish assemblage of the Laja River, Guanajuato, central Mexico." Aquatic Conservation: Marine and Freshwater Ecosystems 16, no. 5 (2006): 533-546.
  • Safe, Stephen. "Polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and related compounds: environmental and mechanistic considerations which support the development of toxic equivalency factors (TEFs)." CRC Critical Reviews in Toxicology 21, no. 1 (1990): 51-88.
  • Ziadat, Anf H., and Emad Sood. "An Environmental Impact Assessment of the Open Burning of Scrap Tires." Journal of Applied Sciences 14, no. 21 (2014): 2695.

Continue reading at AIR POLLUTANTS, COMMON INDOOR or select a topic from the More Reading links or topic ARTICLE INDEX shown below.

Or see San Miguel de Allende - 88 Great Photographs and other articles about San Miguel de Allende in Guanajuato, Mexico.

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AIR QUALITY STUDY San Miguel de Allende at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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