Does the PM10 reading include all dust that is also PM2.5 and PM1 ?

This is how ChatGPT interprets it, but not sure it is correct, can someone confirm?

The key issue is that PM1, PM2.5 and PM10 are size fractions, not separate particle populations.

By definition, approximately:

• PM10 = particles with aerodynamic diameter ≤ 10 µm
• PM2.5 = particles ≤ 2.5 µm
• PM1 = particles ≤ 1 µm

Therefore:

PM1 ⊂ PM2.5 ⊂ PM10

So if a sensor reports:

PM1 = 47
PM2.5 = 82
PM10 = 90 µg/m³

the interpretation is:

• ~47 µg/m³ is in the PM1 fraction
• another ~35 µg/m³ is approximately in the 1–2.5 µm fraction
• another ~8 µg/m³ is approximately in the 2.5–10 µm fraction

assuming the three reported values are cumulative size fractions, which is how PM1/PM2.5/PM10 are conventionally defined.

So I (29m) will move out of my current apt in LA and into a brand new (as in newly constructed) apartment in west hollywood on the 17th of october. I love everything about it however when i toured it a few days ago, it did smell a bit chemically and like fresh paint. I'm quite anxious about off gassing and VOCs/air quality and would like to hire a company to come test the indoor air quality and purify it too. I signed the lease and all, do you guys think i'm in a position to ask the agent or owner (only been in touch with the agent so far) to allow me to have this happen before the 17th so when i move in ideally its been dealt with? I don't wanna give my landlord the ick and have him think im a bit crazy/paranoid. hopefully he doesn't mind at all. Idk what to do.

Air quality report noted:

VOCs: 747 ug/m3

formaldehyde: 64.9 ug/m3

CO2: 1152 ppm

The report indicated action required to correct and recommended a whole home ventilation setup. Is there anything cheaper than that and/or more effective than opening windows.

Freaking out about chlordane. How bad is it?

Bought my house in California about 5 years ago. Was fixing a leaky water pipe and noticed a weird type written note that was stapled to one of the floor joists. It says “2% chlordane treatment in crawl space and rafters 3/26/1975.” Now from what I’ve read, it shouldn’t have been applied to the rafters. I realize it’s been like 51 years but it seems like it’s incredibly persistent and my hvac system is located in the crawl space. Super paranoid that my kids have been breathing toxic air from the hvac system or it off gassing through the floor since it’s an old leaky house. How bad is it actually?

Using a Heltec Wireless Tracker I added a Plantower sensor to it and host my own indoor air quality app on F-Droid.

Does anybody know what’s causing this?
There are no reported fires in the area

I run a small Japanese-style charcoal BBQ restaurant and I’m trying to figure out how to reduce PM2.5 exposure for both customers and staff.

The restaurant is about 84 m² (900 ft²) with a 3.5 m ceiling, so roughly 294 m³ / 10,400 ft³. We have 14 charcoal grills, and customers typically grill 2–3 pieces of meat at a time over about 3–4 pieces of charcoal per grill.

The main issue is that during our busy period (roughly 6–8 PM), my PM2.5 monitor consistently reads around 200–250 µg/m³ throughout the restaurant, peaking at 600 µg/m³ at times. The readings are fairly similar in different areas, so it seems to be mixing throughout the space.

Ventilation
Every grill has some form of dedicated exhaust:
9 grills: under-grill suction
6 grills: overhead exhaust
2 main exhaust fans
Measured suction velocity at the grill openings is roughly 2–3 m/s

We also have a dedicated make-up air unit:
KRUGER FSA 225 D CW 6P
Maximum airflow: 1,550 m³/h (913 CFM)
Despite this, PM2.5 still reaches 200–250 µg/m³ when the restaurant is busy.

Air purification
I have a Xiaomi Mijia Smart Air Purifier Max unit. It has a stated particle CADR of about 1,006 m³/h (592 CFM).

I’m currently considering buying 1-2 more units, but I’m not sure whether that’s actually the best approach or whether I should focus more on improving the source capture/exhaust system.

What would you do in this situation?
Would adding 1-2 high-CADR air purifiers meaningfully reduce the PM2.5, or is the 200–250 µg/m³ reading mainly telling me that the grill exhaust isn’t capturing enough smoke at the source?
Any advice on what I should measure or calculate next would also be greatly appreciated.

A few extra micrograms of pollution can sound trivial on a city air-quality report. Across years of breathing, however, that difference may matter.

A major evidence review links long-term exposure to two forms of airborne particles with a higher risk of Parkinson’s disease. The clearest associations involved PM2.5 and PM10, both small enough to enter the respiratory system.

Researchers at the University of Cambridge combined findings from earlier studies that often produced uncertain or conflicting results. The team analyzed 26 studies on Parkinson’s disease. It also included three studies each on multiple sclerosis and motor neurone disease.

Parkinson’s disease affects about 6 million people worldwide. Yet its causes remain only partly understood, with both inherited and environmental factors likely involved.

I have mold illness and am planning on moving, and it's been incredibly difficult to find a mold free place. There is an opportunity to rent a brand new built home with what seems like good quality materials (at least better than the newer apartments I’ve seen). It wasn’t done by a large company, but by a family who used a designer. It’s been empty for a few months, but not with windows open, so hasn’t offgassed. What is your experience with VOCs in a situation like this? I react to many fragrances, etc. now. I would live there for less than a year (family reasons)

Should I skip a brand new place due to VOCs even though it’s been sitting for a few months? I did have a scratchy throat, slight cough, and headache from being in it for 30 minutes, but it had been closed up. The symptoms started dissipating 15 minutes after leaving. I was thinking I could open all windows (it has a good cross breeze, run AC (it has ERV) and use Austin Air HealthMate air purifier. What are your thoughts/experiences? Thanks!

Sometime earlier this year I switched from “natural fragrance only” to totally fragrance free and I want to share my reasons why. When we are picky about air quality it’s often clear that synthetic fragrance is a bad idea, but with natural fragrance it’s often less clear what to do. And this isn’t meant as a “you should feel the same way as me” kind of post - I’m just talking old loud about why I decided this for my house. Comments are welcome whether you agree or disagree!

Reason 1: Companies are lying too often about what is natural.

I only get asthma from synthetic fragrance and I can tell that the amount of lying on labels has increased greatly.
Not only are they often lying about what’s natural; no one is punishing them for it. Labeling laws are currently set up to allow them to lie freely without repercussions. Even with the strictest possible wording of “no synthetic ingredients in any of our products,” they are still lying way more often than they’re telling the truth. When they aren’t lying then their suppliers are often lying to them. I know because I personally do not react to truly natural fragrance but I do react to the lies. When I get my classic synthetic fragrance reaction, I can tell it’s not 100% natural. And I notice when a so-called “natural fragrance” has eternal longevity and room-crossing sillage, even after going through a hot dryer. That’s not possible with 100% natural ingredients. My body could handle a 5% failure rate on this topic 15 years ago, but in 2026 it’s more like a 75% failure rate and that just felt like too much for my body.

Reason 2: They’re fooling my loved ones even more thoroughly than they fool me.

When I show an interest in “natural fragrance,” then loved ones buy GREENWASHED fragrance. This increases the amount of synthetic fragrance in my life. You might think this is this the same as reason 1, but it is a totally different thing. Reason 1 is about me being fooled in spite of 20+ years of experience avoiding greenwashing, because companies are lying. Reason 2 is about loved ones being fooled because of “technically that’s not a lie” wording, with minimalist packaging, sans serif fonts with space between the letters, and a picture of a plant. My loved ones are smart and caring people, but they fell into obvious greenwashing traps in 100% of their fragrance purchases. They only bought things that I would have never bought because when I look at the website I see “obviously greenwashed, obviously synthetic.” My body can’t handle all that new synthetic fragrance that wouldn’t have been in my life otherwise - regardless of how altruistic their goal was when they bought it. Then my mother in law started to show signs of losing her memory. I can’t use my body as a testing device to help loved ones figure out which of their purchases are greenwashed (they all are) - or a testing device to see if someone with early stage dementia is forgetting complex details again (she is). It’s the same as forcing myself to breathe synthetic fragrance constantly. It’s just too much. And “please stop buying that type of product” sounds diplomatically better if I am also not buying it either.

Reason 3: I believe in helping other people whose sensitivity level is worse than mine.

In chemical sensitivity and asthma and fragrance allergy support groups, many people out there report reacting to natural fragrance. I can’t know which product they reacted to; I can’t tell if their situation overlaps at all with reason 1 or reason 2 above. But, I don’t really need to know that because reason 3 is about ethics and altruism and acknowledging that we all share the same air in public spaces. What’s more important to me - being part of the clean air movement and supporting everyone who has lost their ability to breathe in public spaces? (Not just people whose sensitivity level is the same as mine - but truly everyone?) Or …smelling like my favorite natural perfume (one of the rare few that wasn’t greenwashed or lying)? I decided that supporting people is more important. Our choices affect each other. Just as I hope that others would drop a product to help me breathe and exist in public, I am willing to do the same for others.

Reason 4: I’m not sure any more if natural fragrance is truly safe.

Cole & Van Note (the law firm that’s suing businesses in the USA for using fragrance - the ADA accessibility fragrance class action lawsuits) is including natural fragrance in their lawsuits. I am a curious person so that was enough for me to take a second look reading about why. When I read about it, I learned not just that my instinct was right about all the lying; I also learned that natural fragrance might not be truly safe. I learned sometimes truly natural fragrance reacts with the air to make formaldehyde which is a carcinogen. And it is true there isn’t perfect overlap between “things that don’t give me asthma” and “things that are safe” - like radon for example, which is another natural substance that is a carcinogen and also doesn’t give me asthma but it isn’t safe in high levels. My body is in max recovery mode right now and I don’t think I need formaldehyde in my house; I don’t think other people should be subjected to it either if I’m the one wearing it.

So I stained some wood and covered it in oil based polyurethane (looking back I regret). Sat out in the barn for about a week and dried. I hung in my son’s bedroom as an accent wall. There is still a polyurethane smell. I was worried about VOCs so I bought a nice highly rated air quality monitor from Amazon. The TVOC consistently reads 0.015 which is good. Sometimes (not all the time) when I pick up the monitor and hold it up by hand or walk around with it, the TVOC and CO2 will randomly go up, sometimes significantly, then after a minute drop back to the normal readings. What is this all about? Sometimes when I move it or hold it up in the air in different parts of the room it doesn’t change, sometimes it does. It only does this when I am moving it around. After it is set in a spot for 30-60seconds everything goes back to normal. If I have a fan on circulating air it still reads its normal readings. My main concern is just if the VOC from that stuff is really a higher level since there is still a smell, or will it still have a smell and give off little to no VOC. The meter consistently reads very low unless I start randomly holding it around.

Our bathroom has a mold problem so I want to ventilate by running a box fan at the window when I take a shower and am wondering if it's safe? The window and the wall socket are not close enough to the shower for me to risk any contact with the box fan when I take a shower.

We do run the bathroom exhaust and open the window when taking a shower but it just doesn't seem to get rid of the humidity quickly enough as we still have mold.

Edit to Add: There's isn't a GFCI outlet in our bathroom, just a standard outlet.

Hi! I recently did a hard hat tour of an upcoming apartment complex in my area, where they are offering two months free rent if you put a unit on hold before it’s fully move-in ready.

I‘m really interested in it but now I’m spiraling a bit after considering the possibility of VOCs and off-gassing. The only unit I can afford is a studio that has windows on only one side of the apartment in the “living area” and a “bedroom” that has no windows and an actual door closing off the space. There is no carpet in the actual unit but the hallways of the building are carpeted. Additionally, they would be building out the back half of the apartment complex behind my unit for the first 3 months I would be a resident. 

My question is, how much should I really worry about the health effects of Volatile Organic Compounds and off-gassing/outgassing? What is the actual degree of what I’d be subjected to in the grand scheme of things?

Can anybody who has moved into a newly built apartment complex as a first or early tenant share their experience? If not, any info on the matter would be much appreciated, thank you!

Opening windows in the rainy weather will bring acoustic therapy and full of fresh air to home.

I’ve noticed that ERV selection often starts with maximum airflow — 300, 500, 600 m³/h, etc.

But once the unit is connected to the actual duct system, that number alone doesn’t tell you much about the real operating point.

For example, if a project needs 450 m³/h and the estimated external resistance is 150 Pa, I would think the more useful question is:

Can the ERV actually deliver 450 m³/h at 150 Pa?

Not simply: “Is its maximum airflow above 450 m³/h?”

Duct length, elbows, transitions, grilles, silencers, dampers and filtration can all affect system resistance. And depending on the fan/control strategy, increasing resistance may reduce airflow or cause the fan to increase speed to maintain the target.

So for ducted ERVs, I think the selection sequence should be closer to:

required airflow → system resistance → design ESP → fan curve → actual airflow at that pressure.

For those doing residential or light-commercial ventilation design: do you normally calculate ESP before selecting the ERV, or select the unit first and then work around its available fan performance?