# Introduction to Air quality ## What is ideal air? - **Temperature:** 20–22°C (18–19°C for sleeping) - **Humidity:** 40-60% RH - **CO2:** <600ppm - **VOC:** <300ppb - **PM2.5:** <10ug/m3 ## CO2 - Levels & effects - High CO2 mimics sleep deprivation — **feel tired or off without noticing**. - **Cognition drops quickly and linearly with CO2 levels.** - ~945 ppm: 15% lower cognition. - ~1,400 ppm: 50% lower cognition (common in small rooms). - **CO2 Levels** - 500 ppm: ideal (outdoors or with open windows). - 1,000 ppm: typical indoors; start feeling tired. - 1,500+ ppm: common in closed spaces (offices, gyms, cafes); unhealthy. Headaches can start around 1500 ppm. - 5000+ ppm: is dangerous. - **Typical experiments that you can run home with a CO2 monitor**: - You'll notice a huge difference between keeping the door and windows closed versus opening them just 1 cm. You go from 800–1500 ppm down to 450–550 ppm (close to the 400 ppm of outdoor air). - There is usually a spike during the night if you keep all your windows and doors closed and sleep in a relatively small room. That might explain why you wake up tired. - Ventilating while cooking (especially with combustion) significantly reduces the amount of microparticles and CO2 indoors. ![[CO2 - Air quality.png]] ## Mold risks - Above 65% humidity encourages mold growth. - Mold is a major health risk, more common than formaldehyde issues. - First signs: black spots on bathroom caulking. ## How to fix indoor air - **CO2**: Open windows, run HVAC fan. Filters don't remove CO2. - **Particles**: Use MERV-11 filters or air purifiers. - **Humidity**: Proper HVAC maintenance handles it. ## Indoor plants? No significant impact - Look good, boost mood, but barely impact air quality. - One plant absorbs less CO2 yearly than a person emits daily. - Real ventilation is far more effective than plants. ## TL;DR on indoor air quality - Bring in fresh air (especially during the night and while cooking) - Plants don't help much - High CO2 fogs thinking - Measure to detect problems - Use better filters # Monitoring air quality ## Air quality in real-time around the world - Real-time Air quality index - Map: [World's Air Pollution](https://waqi.info/) (PM 2.5, PM 10) - Live map: [Live Animated Air Quality Map (AQI, PM2.5...) | IQAir](https://www.iqair.com/air-quality-map) - Live major city ranking: [World Air Quality Index (AQI) Ranking | IQAir](https://www.iqair.com/world-air-quality-ranking) ## Home air quality monitors Two of the best ones: - Aranet4 - Mostly for CO2 - [[aranet4-quick-start-guide-eng-v050924.pdf]] - Pros - Simple air quality monitor for CO2, temperature and humidity, - Easy to travel with - Months of autonomy - Cons - No particle measurement (PM2.5, PM10) - [Qingping 2 -Amazon.fr](https://www.amazon.fr/Qingping-D%C3%A9tecteur-Int%C3%A9rieur-Temp%C3%A9rature-Intelligente/dp/B0CZ886B8N/) - Pros - Great advanced air quality monitor: PM2.5, CO2, PM10, noise, temperature, humidity - Cons - Hours of autonomy # Improving the air you breathe ## Home air purifiers? MERV 13 / HEPA - Air purifiers are a no-brainer if you're asthmatic or allergic populations (e.g., pollen, dust mite, etc.); otherwise, you can still get one by default, especially if several people live in the apartment (to catch fewer microbes from each other). - Bryan Johson - [X post](https://x.com/bryan_johnson/status/1886879502007173387/photo/1): - Improve the air quality in your home, apartment, office and gym by upgrading the air filter in the HVAC system. - The higher the MERV filter, the better. Not all HVAC systems can handle the higher MERV filter so get the best one you can. - Try to have **MERV 13 at a minimum**. - [Air Pollution Is Killing Us - YouTube](https://www.youtube.com/watch?v=l4-VkQ6SxoE&ab_channel=BryanJohnson) ![[MERV filters.png]] - Each MERV rating corresponds to a filter's efficiency in capturing particles of different sizes (measured in microns): | MERV Rating | Particle Size Captured | Common Uses | | ----------- | ------------------------------------------------------- | --------------------------------------------- | | MERV 1-4 | 10+ microns (dust, lint, pollen) | Basic residential HVAC, window AC units | | MERV 5-8 | 3-10 microns (mold spores, pet dander) | Better home filters, commercial buildings | | MERV 9-12 | 1-3 microns (PM10, lead dust, some bacteria) | High-quality home filters, hospitals, offices | | MERV 13-16 | 0.3-1 microns (PM2.5, smoke, viruses, allergens) | Best for home use, healthcare, schools | | MERV 17-20 | <0.3 microns (viruses, aerosols, radioactive particles) | Cleanrooms, hospitals, HEPA-level filtration | - **What to buy - Best option from the Wirecutter benchmarks** - [Coway Airmega Mighty](https://www.amazon.fr/stores/COWAY/CowayAirmegaMighty_CowayAirmega/page/CC714C82-5948-47B6-B3FC-733B6591B866) ## Face masks outside? Mostly, if you're allergic or are in a very polluted city ### Introduction on face masks FFP3 is the best face mask category: | Category | Aerosols filtering | Leakage to the outside | | -------- | ------------------ | ---------------------- | | FFP1 | 80% | 22% | | FFP2 | 94% | 8% | | FFP3 | 99% | 2% | - Best mask is probably the: 3M Particulate Respirator, FFP3, Valved. Easy to find on Amazon. - Alternatively, you can check that your mask is HEPA level (99.95% filtering of particles) ### Air pollution vs cycling/walking/car - Commuting - Interesting: [The Guardian video](https://www.theguardian.com/environment/video/2014/aug/12/london-air-pollution-public-transport-video) - There is 5x more exposure to pollutants when you're in a car or bus compared to walking or cycling. - Same as for asthma or allergies: getting a mask is a no-brainer. - Mask effectiveness decreases with longer wear time: moisture buildup reduces their performance. - [Can air pollution negate the health benefits of cycling and walking? - ScienceDirect](https://www.sciencedirect.com/science/article/pii/S0091743516000402) - June 2016 - TL;DR: No, air pollution doesn't negate the health benefits of cycling and walking (without any face mask). - **Air pollution vs face masks**: [(PDF) Effectiveness of face masks used to protect Beijing residents against particulate air pollution - Research Gate](https://www.researchgate.net/publication/324384284_Effectiveness_of_face_masks_used_to_protect_Beijing_residents_against_particulate_air_pollution) - April 2018 - TL;DR: Some face masks actually work against air pollution, but how good a model is depends a lot on the compatibility between your face and that model.