The air we breathe underground
Subway air is full of pollution.
Numa filters it — every breath.
Subway air is thick with fine-particle pollution you can't see — and it's linked to real harm to your lungs. Here's what you're actually breathing underground.
The invisible commute
When the train's headlights cut through the tunnel, you see it: a fog of suspended particles. You've been breathing it the whole time.
Subway air is loaded with fine particulate matter — brake dust, rail wear, and debris — at levels that dwarf the air above ground. It's invisible, it's chronic, and right now most commuters just live with it.
What that air does to your body
At under 2.5 microns, these particles slip past your airways' defenses — deep into the lungs, and into the bloodstream.
Short-term spikes are linked to asthma and allergy flare-ups, airway inflammation, and reduced lung function.
Fine-particle exposure is tied to cardiovascular stress — a measurable drop in heart-rate variability after a single subway trip.
Long-term PM2.5 exposure raises the risk of chronic respiratory and cardiovascular disease. The dose compounds over years.
Environmental Science & Technology (PM2.5 health effects) · Harvard Six Cities Study · WHO air-quality guidelines · NYU Langone subway-exposure pilot study
This isn't ordinary city dust. Subway PM2.5 is chemically distinct — high in iron oxide from brake and rail wear, plus elemental carbon — raising concerns beyond standard particulate exposure. And transit ventilation is "often inefficient" at removing it, which is exactly why personal protection matters.
Luglio et al., Environmental Health Perspectives 2021 (NYU Langone) · Env. Science: Processes & Impacts, review of 130+ studies, 2021
The job to be done — and why today's options fail
The job: protect my lungs on the commute I take anyway — without a mask, without effort, without anyone noticing. That's the gap Numa fills.
What we're building
Awareness is step one. This is step two.
Knowing about the air isn't enough — you need a way to do something about it. So we're building Numa: a discreet nasal device that filters the air you actually breathe. No mask, no effort. Designed to clean any air for anyone, and built first for subway riders with asthma and allergies.
Breathe naturally
Engineered for low airflow resistance, so a 30–60 minute commute feels effortless — not like breathing through a straw.
Practically invisible
A discreet in-nose insert, not a face mask. Socially weightless — wear it on a packed platform, nobody notices.
Layered protection
Multiple filter layers capture coarse debris, fine PM2.5, and odor — then pop out and swap when spent.
Like what you see? It's free to reserve.
No product yet, no payment today — just tell us you'd want one. That's the signal that gets it built.
The evidence
Not a hunch. A documented health problem.
Peer-reviewed research from credible institutions confirms subway air quality is a real, measurable public-health concern — not an anecdote.
Mean PM2.5 measured on NYC subway platforms — versus 99 on trains. Roughly 9× the WHO daily limit.
PM2.5 in London & Stockholm subways runs about ten times higher than the ambient air above ground.
Long-distance commuters are 25% of riders but bear 40% of the total health burden — exposure compounds with time.
Questions, answered
Everything you're probably wondering.
Does it make breathing harder?
What if I breathe through my mouth?
Will it fall out when I talk, sneeze, or run for the train?
Is it comfortable for a full commute?
How do I keep it clean, and how often do I replace the filter?
Is it safe? What's it made of?
Does it actually help with asthma or allergies?
There's no product yet — so what am I paying?
Reserve · Founding run
Be first. And help decide if this gets built.
No product exists yet — your reservation is the signal that tells us to build it. It takes ten seconds, costs $0 today, and there's no card. Hit our number and you get the first units off the line at founding-member pricing.
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