A diverse group of citizen scientists monitoring air quality using biomonitors.

Is Air Pollution Silently Harming Your Health? How Citizen Scientists Are Fighting Back

Mira Elwood monogram
Mira Elwood in Climate & Environment October 2026 • 4 min read.

"Uncover the hidden dangers of nitrogen deposition and how everyday tools can help monitor air quality and protect your well-being."


In today’s world, air pollution is a significant threat to our environment and human health, especially in densely populated areas. An increase in nitrogen deposition, stemming from human activities, is a major concern. While governments and large research bodies monitor air quality, many individuals and communities want a way to take action themselves.

Reactive nitrogen species in the atmosphere, such as NOx and NHx, contribute to the creation of particulate matter and tropospheric ozone, impacting respiratory and heart health. In places like Mexico City, air pollution contributes to thousands of deaths annually. This is where atmospheric biomonitors come in handy.

Biomonitors offer a practical and affordable solution for monitoring air quality. Rather than relying on expensive air quality monitoring networks, widely distributed biological species can provide insights into the levels of nitrogen deposition. These biomonitors include lichens, mosses, and bromeliads, which respond to environmental changes in measurable ways.

AI Search Multiple angles on this topic

Why Air Pollution Matters

Air pollution can affect health without always producing obvious immediate symptoms. Its effects may vary with the pollutant, exposure level, duration, and a person's underlying health. Understanding those risks requires reliable measurements as well as attention to how exposure occurs in daily life.

How Air Quality Is Measured

Standard public-facing approaches commonly use color-coded Air Quality Index systems to summarize local conditions. Oregon's Department of Environmental Quality provides this information through more than 37 monitoring stations, allowing users to select a station on a map and view nearby air quality. Forecast services such as AccuWeather present Salem conditions hour by hour to help people plan outdoor activities, while GAIA monitors can provide real-time readings through maps and an API after connecting to Wi-Fi and a USB-compatible power supply. These tools improve access to information, but their usefulness depends on the monitoring location, the information provided, and how well local readings represent an individual's exposure.

The Rise of Real-Time Reporting

Public air-quality reporting has increasingly emphasized real-time access to local conditions. The Salem AQI service reports current air quality and AQI levels for Salem in Marion County, Oregon. This kind of location-specific reporting provides a practical foundation for tracking pollution conditions over time, although the source does not by itself document a longer historical timeline or specific scientific milestone.

What are Atmospheric Biomonitors and How Do They Work?

A diverse group of citizen scientists monitoring air quality using biomonitors.

Atmospheric biomonitors are plant species that can indicate the ecological health of an environment. These organisms respond in measureable ways to atmospheric pollutants. The focus research studied lichens, mosses, and bromeliads around the Valley of Mexico to assess their viability.

Here’s how the biomonitors responded:

  • Lichens (Anaptychia sp.): Showed significant responses in nitrogen content, C:N ratio, and δ15N values relative to season and site.
  • Mosses (Grimmia sp. and Fabronia sp.): Displayed a linear response in δ15N to wet deposition, reflecting nitrogen content based on season and site.
  • Bromeliads (Tillandsia recurvata): Demonstrated a linear response to NOx in nitrogen content, C:N ratio, and δ15N values. High nitrogen disrupted its usability as a biomonitor.
AI Search Multiple angles on this topic

An Evolving Evidence Base

Research on air pollution and health continues to develop as scientists improve measurement methods and study designs. Findings may differ depending on the pollutants examined, the populations observed, and the length of exposure considered. Readers should therefore treat emerging conclusions as evidence that may be refined as additional research becomes available.

Limits of Air-Quality Claims

Air-quality information does not automatically reveal every person's actual exposure or health response. Measurements can be limited by where monitors are placed, how often conditions are recorded, and whether a single reading reflects changing local circumstances. These limitations do not make monitoring useless, but they caution against treating any one measurement as a complete account of risk.

Comparing Pollution Evidence

Comparisons of air-pollution conditions are meaningful only when the locations, pollutants, time periods, and measurement methods are comparable. A difference in reported air quality may reflect genuine environmental variation, but it may also reflect differences in monitoring coverage or reporting practices. Careful comparisons should therefore identify both what the available measurements show and what they cannot establish.

These organisms accumulate pollutants in their tissues. By studying these concentrations, the researchers could then infer the degree of environmental contamination. The study assessed these organisms' nitrogen metabolism parameters, including nitrogen content, carbon-to-nitrogen (C:N) ratio, and nitrogen isotope composition (δ15N).

How Can This Information Be Used?

The study shows how combining various biomonitors can reliably indicate nitrogen deposition. Regular citizens can collect and analyze lichens, mosses, and bromeliads. Doing so will determine the status of atmospheric nitrogenous pollution in areas without formal monitoring networks. This community data can inform public health and environmental policies, leading to more effective pollution control measures and improving overall environmental quality.

AI Search Multiple angles on this topic

From Measurements to Meaning

Air-quality monitoring can make an otherwise invisible environmental condition easier to understand. Its greatest value comes from combining accessible measurements with careful interpretation of location, timing, and uncertainty. The available evidence supports informed awareness, while avoiding claims that exceed what the measurements can demonstrate.

A More Connected Monitoring Future

Future air-quality monitoring may become more useful as public agencies, community groups, and individuals gain access to timely local data. Expanding coverage could help reveal conditions that broad regional summaries miss. At the same time, better interpretation and transparent communication will remain important as monitoring networks grow.

The Challenge Beyond a Single Reading

Air pollution is shaped by environmental conditions, built environments, transportation, industry, and patterns of human activity. A single monitor or forecast can describe conditions at a particular place and time but cannot capture every source or exposure pathway. Addressing the problem therefore requires both dependable information and broader efforts to reduce pollution at its sources.

Making Air Data Useful

People use air-quality information to decide when to exercise outdoors, travel, or take other precautions. Clear local reporting can turn an abstract environmental concern into information relevant to everyday choices. Its real-world impact depends on whether people can access the data, understand its limits, and use it in ways appropriate to their circumstances.

The Valley of Mexico biomonitoring study at a glance

PopulationA lichen, two mosses, and a bromeliad[1]
SettingValley of Mexico[1]
Main outcomeNitrogen content, C:N ratio, and δ15N responses to season and site[1]
Effect sizeFor the bromeliad, nitrogen content R2 = 0.7, C:N ratio R2 = 0.6, and δ15N R2 = 0.5 showed linear responses to NOx.[1]
Times cited20[1]

What the measured nitrogen levels show

  • 1.3%Moss nitrogen content was 1.3% at a protected northern site, where deposition was 5.0 kg N ha−1 year−1; at a site north of Mexico City, it was 3.8% alongside deposition of 40 kg N ha−1 year−1.[2]
  • 1.4%In Anaptychia, nitrogen content ranged from 1.4% of dry mass in a protected area to 5.0% at an urban site during the dry season.[2]
  • 23Mexico City's wet nitrogen deposition rose from 23 to 45 kg ha−1 year−1 across the east-to-west range in 2013, and from 24 to 50 kg ha−1 year−1 in 2014.[2]

How these biomonitors compare across pollutants

This paper proposed using multiple biomonitors together because physiological constraints can blur the deposition signal. Other work describes native moss as a way to reflect deposition over months to years, while a separate urban lichen study found signatures consistent with a mixture of airborne NOx and NHx compounds.[1] [3] [4]

What tissue measurements can reveal about nitrogen

Because mosses lack a cuticle and vascular system, incoming pollution can be assimilated readily, especially from wet deposition. That helps explain why moss measurements may capture deposition patterns that do not mirror the city's dominant gas pollutant.[2]

Biomonitors can reflect deposition over extended periods, so their measurements describe accumulated environmental signals rather than only a momentary airborne concentration.[3] [4]

Where the biomonitor signals are weakest

  • Moss uptake of gaseous pollution may weaken during the dry season because dormant plants cannot physiologically take up the gas.[2]
  • Plant nitrogen measures can respond to influences besides nitrogen pollution, so observed differences should not automatically be attributed to deposition alone.[2]

What a follow-up would need to resolve

  • How well do the species' nitrogen signals distinguish deposition from other environmental influences on their measured parameters?[1] [2]

Sources

  1. Characterization of nitrogen deposition in a megalopolis by means of atmospheric biomonitors (Springer Science and Business Media LLC, 2018)
  2. Characterization of nitrogen deposition in a megalopolis by means of atmospheric biomonitors (Europe PMC, 2018)
  3. Putting biomonitors to work: native moss as a screening tool for solid waste incineration (pmc.ncbi.nlm.nih.gov)
  4. High spatial resolution assessment of air quality in urban centres using lichen carbon, nitrogen and sulfur contents and stable-isotope-ratio signatures. (pubmed.ncbi.nlm.nih.gov)

About this Article -

Written with AI assistance from published research, and reviewed by the Mystum team. See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1038/s41598-018-32000-5, Alternate LINK

Title: Characterization Of Nitrogen Deposition In A Megalopolis By Means Of Atmospheric Biomonitors

Subject: Multidisciplinary

Journal: Scientific Reports

Publisher: Springer Science and Business Media LLC

Authors: Edison A. Díaz-Álvarez, Erick De La Barrera

Published: 2018-09-11

Everything You Need To Know

1

What is nitrogen deposition, and why should I be concerned about it?

Nitrogen deposition refers to the process where reactive nitrogen compounds, produced largely by human activities, are deposited from the atmosphere onto land and water surfaces. This includes various forms of nitrogen, such as NOx and NHx. Excessive nitrogen deposition can lead to several environmental and health problems, including the creation of particulate matter, tropospheric ozone, and the disruption of ecosystem balance. In affected areas, reactive nitrogen can affect both respiratory and heart health.

2

What exactly are atmospheric biomonitors, and how do they help in assessing air quality?

Atmospheric biomonitors are plant species, like lichens (Anaptychia sp.), mosses (Grimmia sp. and Fabronia sp.), and bromeliads (Tillandsia recurvata), that respond measurably to changes in air quality. They accumulate pollutants in their tissues. By analyzing the nitrogen content, carbon-to-nitrogen (C:N) ratio, and nitrogen isotope composition (δ15N) in these organisms, scientists and citizen scientists can infer the degree of atmospheric nitrogen pollution in a specific area.

3

How do lichens, mosses, and bromeliads individually respond to varying levels of nitrogen deposition?

Lichens (Anaptychia sp.) respond to nitrogen deposition by changing their nitrogen content, C:N ratio, and δ15N values based on seasonal and site-specific conditions. Mosses (Grimmia sp. and Fabronia sp.) show a linear relationship between their δ15N values and wet nitrogen deposition. Bromeliads (Tillandsia recurvata) display a linear response in their nitrogen content, C:N ratio, and δ15N values to NOx levels, but very high nitrogen levels can make them unreliable as biomonitors. Therefore, the health and composition of these species provides insight into air quality.

4

As a citizen scientist, how can I contribute to monitoring nitrogen pollution using these biomonitors?

Citizen scientists can collect lichens, mosses, and bromeliads from their local environments and send them to labs for analysis of nitrogen content, C:N ratio, and δ15N values. This data, when combined with data from other community members, can provide a comprehensive picture of nitrogen pollution levels across a wider area than traditional monitoring networks cover. These findings can then inform public health initiatives and environmental policies, potentially leading to better pollution control measures and improved environmental quality. This allows regular citizens to engage in environmental protection.

5

Are there limitations to using lichens, mosses, and bromeliads as air quality indicators, and what other factors should be considered for a more complete assessment?

While lichens, mosses and bromeliads are very useful, they might not capture the full spectrum of pollutants present in the atmosphere. Other pollutants, like sulfur dioxide and heavy metals, also pose significant risks to both human health and the environment. Future research could explore the use of additional biomonitor species or combine biomonitoring with other monitoring techniques to gain a more comprehensive assessment of overall air quality. This would provide a more complete picture of the various pollutants affecting the air we breathe.

Newsletter Subscribe

Subscribe to get the latest articles and insights directly in your inbox.