What is causing the high pm2.5 readings and mist/haze in the morning?

[chirhone]

Mist or fog is said to be caused by water vapor while haze is caused by pollution. Every morning i got high pm2.5 readings in both my plantower 5003 and dylos testers which became half by midday. And humdity is high in early morning with haze (or is it mist) in the background of the city. This is taken at 6:18am.

This is taken with my pm2.5 sensors and humidity meter.

 

[PhanthomJay]

I’d call it haze. Haze reduces horizontal visibility to about 10 km (7 miles) or less. Mist is usually already in the air in which you are standing, with relatively high humidity. Relative humidity in the morning hours tend to be high regardless of haze or mist because temperatures are lower.

 

[Klystron]

In the Western USA we use the colloquial expression smog derived from smoke + fog to describe mist/haze over cities.

 

[anorlunda]

I've heard that much of the haze is due to ozone in the air. It that correct?

About 10 years ago while on a ranger guided tour at the Grand Canyon, the ranger pointed out the Navaho power plant visible 100 miles away. He said that it was no longer visible on most days because of haze. I wonder how far back the weather bureau has records of visibility.

 

[chirhone]

I’d call it haze. Haze reduces horizontal visibility to about 10 km (7 miles) or less. Mist is usually already in the air in which you are standing, with relatively high humidity. Relative humidity in the morning hours tend to be high regardless of haze or mist because temperatures are lower.

I live in the 32th floor. Can mist gets as high as 32 floor? Doesnt mist also reduces visibility? In the picture earlier. Visibility is not affected to 10 km or less. How does mist look like when it covers whole city?

 

[jim mcnamara]

https://www.ncdc.noaa.gov/data-access/land-based-station-data
This product has visibility data along with many other datasets.

 

[chirhone]

In the Western USA we use the colloquial expression smog derived from smoke + fog to describe mist/haze over cities.

Here is picture taken same day at 1:19pm after noon:

Here is the one taken same day at 6:18am early morning. Why did the haze or mist seem to gravitate during the night and gone as early as 10am? Where did it go?

 

[Klystron]

Years ago I lived in San Diego in California; then a much smaller city then now on the south-eastern coast of the Pacific Ocean. Most mornings in summer after the night fog receded everything outdoors was covered with a black film apparently from condensed smog that had drifted south from Los Angeles, a much larger industrial metropolitan area and/or from petroleum plants to the north and east.

In the San Francisco Bay Area we call the night time ocean fog 'nature's air conditioning' as it sweeps inland at night, cools the warmer inland valleys and dissipates in the morning. You do not mention your locale but if this city is near a large body of water there may be a similar effect. Otherwise, pollution may blow away like sandstorms in the Sahara deposit sand particles across Africa and the Atlantic Ocean.

https://en.wikipedia.org/wiki/Atmospheric_circulation

 

[chirhone]

Years ago I lived in San Diego in California; then a much smaller city then now on the south-eastern coast of the Pacific Ocean. Most mornings in summer after the night fog receded everything outdoors was covered with a black film apparently from condensed smog that had drifted south from Los Angeles, a much larger industrial metropolitan area and/or from petroleum plants to the north and east.

In the San Francisco Bay Area we call the night time ocean fog 'nature's air conditioning' as it sweeps inland at night, cools the warmer inland valleys and dissipates in the morning. You do not mention your locale but if this city is near a large body of water there may be a similar effect. Otherwise, pollution may blow away like sandstorms in the Sahara deposit sand particles across Africa and the Atlantic Ocean.

https://en.wikipedia.org/wiki/Atmospheric_circulation

Yes. The front of it is a body of water, the manila bay. Top of the following map. So its not a haze nor mist but nature's air conditioning? No single name for it? Why does it dissipate in the morning?

 

[Klystron]

Yes. The front of it is a body of water, the manila bay. Top of the following map. So its not a haze nor mist but nature's air conditioning? No single name for it? Why does it dissipate in the morning?

The reference to nature's air conditioning is just a metaphor. In California we call this mixture of water vapor and air pollution such as smoke and automobile exhaust: "smog". The night time ocean fog dissipates during the day as the sun warms the air above the dew point.

 

[Tom.G]

Rules-of-thumb regarding your photos comparing early morning to afternoon air.

• If it's white it's likely mist/fog/water vapor.
• If it has a color, smell, taste, or is an eye irritant (yes, Los Angeles air met all four conditions about 35 years ago) then it is haze/pollution/chemical based, perhaps mixed with water vapor.

Minor exception is desert areas with dust storms. Those are the color of the local Earth.

 

[chirhone]

The reference to nature's air conditioning is just a metaphor. In California we call this mixture of water vapor and air pollution such as smoke and automobile exhaust: "smog". The night time ocean fog dissipates during the day as the sun warms the air above the dew point.

Another thing. All the air in room doesn't go to one corner only. It spreads or diffuses. Why does haze composing of pm2.5 particles able to focus on a city. Cant the pollution from car or industrial exhausts simply spread or diffuse around the world? How does pm2.5 particles behave against the air. I read even strong rain can't wash them away. See https://smartairfilters.com/en/blog/rain-washes-away-pollution/

 

[russ_watters]

A few notes:
-Mist or fog is water droplets, not water vapor.
-Mist or fog is nearly opaque whereas water vapor is nearly transparent.
-High humidity alone should not register on a particle counter, but most might.
-Winds tend to be higher during the day and can disperse smog.
-Low morning sun angle makes atmospheric defects more visible.

 

[pbuk]

-Winds and convection tend to be higher during the day and can disperse smog.

 

[russ_watters]

...and convection...

Yep, that's a very good point. Winds are part of convection, but usually considered just the horizontal part. But updrafts are a major factor here.

 

[Klystron]

Interesting information on fog formation. I have traveled through the Philippine Islands many times in the past but never lived there. If conditions are similar to Guam, the Marianas or coastal Southeast Asia than tropical humidity remains a prominent factor assessing climate and the local atmosphere.

chirhone's map shows Manila City not only close to the ocean but likely subject to lake effects as well. Air quality laws and regulations also affect the picture; certainly compared to California and Northwest coastal USA.

 

[chirhone]

Here is todays mist or haze taken at 6:50AM. Its much worse than yesterday:

So its combination of mists and haze. But pm2.5 particles being 2.5 microns or less don't gravitate, so why don't they diffuse to the atmosphere above? I am still trying to confirm whether haze or mist is major portion of it so i can decide whether to buy an 60 sq. mtr air purifier.

This is the particle counts accomplying it exceeding "Very Poor"

Value worse than "Very Poor"

I asked all this so i can know whether to buy an air purifier. Should I? I live in 32th floor. Look at the city picture. The sky is big. Why don't pm2.5 particulate diffuse away into the rest of atmosphere instead of getting in my unit at 32th floor?

 

[chemisttree]

Here is picture taken same day at 1:19pm after noon:

View attachment 256929

Here is the one taken same day at 6:18am early morning. Why did the haze or mist seem to gravitate during the night and gone as early as 10am? Where did it go?

View attachment 256930

This a typical phenomenon. At night the atmosphere calms down with the Sun no longer providing energy for upward mixing and turbulence. Everything concentrates close to the ground. A large amount of that haze could be vehicle emissions or emissions from asphalt plants (the worst!), electrical generation, open fires, etc. Humidity near the ground jumps when the temperature falls and transpiration/ground evaporation contribute to the high relative humidity. This layer hugs the ground, effectively trapping all that near the ground. Also notice the orange tint which could be due to NOx compounds resulting from high temperature combustion. Notice the complete lack of clouds which demonstrates the tranquil nature of the atmosphere. Good time to launch large billowy things like hot air balloons, btw.

Now look at the midday picture. The rising sun begins heating the ground and the air just above it. Warm moist air rises creating a bit of wind and turbulence mixing and diluting the pollutants in a thicker slice of the atmosphere; they appear to largely disappear. The top of this billowy turbulence produces those popcorn clouds when the warm and moist air meets a cooler drier layer aloft. By now you had better have landed your hot air balloon. It’s not fun bouncing around in all that.

 

[chirhone]

This a typical phenomenon. At night the atmosphere calms down with the Sun no longer providing energy for upward mixing and turbulence. Everything concentrates close to the ground. A large amount of that haze could be vehicle emissions or emissions from asphalt plants (the worst!), electrical generation, open fires, etc. Humidity near the ground jumps when the temperature falls and transpiration/ground evaporation contribute to the high relative humidity. This layer hugs the ground, effectively trapping all that near the ground. Also notice the orange tint which could be due to NOx compounds resulting from high temperature combustion. Notice the complete lack of clouds which demonstrates the tranquil nature of the atmosphere. Good time to launch large billowy things like hot air balloons, btw.

Now look at the midday picture. The rising sun begins heating the ground and the air just above it. Warm moist air rises creating a bit of wind and turbulence mixing and diluting the pollutants in a thicker slice of the atmosphere; they appear to largely disappear. The top of this billowy turbulence produces those popcorn clouds when the warm and moist air meets a cooler drier layer aloft. By now you had better have landed your hot air balloon. It’s not fun bouncing around in all that.

In short. Pollution is higher at 4am to 10am or early morning and this is official and occur everywhere? We tend to think pollution is greater at mid day as there are more and more cars.

Also many think pollution is only apparent when they see vehicles or industrial emission. Who would have thought pollution even exist at the 32th floor of a condo unit!

 

[Tom.G]

The reason for that sharp demarcation in the photo of post 17 is an Inversion Layer. That's when there is a layer of cooler air above that traps the warmer air near the ground. Quite common here in the Southern California Summer. The warmer ground air is attributed to the City Effect, where all the pavement and buildings warm up during the day and keep the air warmer at night. At night here there is usually an on-shore breeze bringing the cooler ocean air in, trapping all the smog/haze below it.
(Choke, Choke... not really that bad these days with all the emission restrictions in effect)

Cheers,
Tom

 

[Klystron]

Coincidentally, I found this article in the Washington Post tech section. These are not my opinions but may help your decision.

I run a Honeywell air filter that blows vertically into my overhead air conditioner (AC) plenum filters to

1. trap dust and lint at floor level.
2. act as a pre-filter to extend the life of the ventilation / AC filters.
3. boost air quality while cooking, etc.
4. keep air circulating while the AC is inactive.

The auxiliary air filter performs these tasks with limited efficiency and requires frequent cleaning in my dry dusty low-humidity desert climate. If I did not already own the aux filter bought originally for my asthmatic daughter, I might not buy one. It certainly does not hurt indoor air quality.

https://www.washingtonpost.com/life...c26778-490e-11ea-bdbf-1dfb23249293_story.html

 

[chirhone]

Coincidentally, I found this article in the Washington Post tech section. These are not my opinions but may help your decision.

I run a Honeywell air filter that blows vertically into my overhead air conditioner (AC) plenum filters to

1. trap dust and lint at floor level.
2. act as a pre-filter to extend the life of the ventilation / AC filters.
3. boost air quality while cooking, etc.
4. keep air circulating while the AC is inactive.

The auxiliary air filter performs these tasks with limited efficiency and requires frequent cleaning in my dry dusty low-humidity desert climate. If I did not already own the aux filter bought originally for my asthmatic daughter, I might not buy one. It certainly does not hurt indoor air quality.

https://www.washingtonpost.com/life...c26778-490e-11ea-bdbf-1dfb23249293_story.html

I am not concerned about asthmas or allergies but the simple fact this pollution can get inside your bloodstream and cause diseases. Is this still debatable? see

https://www.google.com/amp/s/www.ne...s-may-enter-your-blood-and-cause-disease/amp/

 

[Barakn]

I agree with some previous commenters that part of what is happening is an inversion layer in the early morning. As sunlight heats the Earth's surface, the temperature difference decreases, but also convection starts to mix layers, allowing fast-moving high altitude air to couple with lower layers, causing them to move faster as well. Sea breezes from land-sea temperature differentials might also be at play.

However, I would not rule out lighting effects related to geometry. In the early morning, sunlight is passing almost horizontally through the atmosphere, meaning that when it is passing low enough, it has a long path length right through the densest haze, giving it more opportunity to scatter. The haze, in effect, casts a shadow on itself. Whereas if you look more vertically, you are looking at light scattered from sunlight that has passed through a thinner part of the atmosphere with less haze and hence is stronger, but also is more likely to be scattered by air molecules than by larger haze particles, and thus the scattered light is bluer. The resulting color and intensity contrast between the haze layer near the horizon vs. blue sky above makes the haze more noticeable in the AM. Closer to noon, the sun is passing through much less atmosphere and less haze and therefore scattering less no matter which direction you look. This flattens out the contrast between the horizon and stuff above it, making it appear as if there might be less haze, when in fact there might be as much or more.

I would recommend relying less on your camera and more on your other meters to figure out whether there is a diurnal pattern in particulate counts.

 

[Klystron]

The Washington Post article mentions several methods to improve indoors air quality including:

1. frequent vacuuming preferably with a HEPA filter on the vacuum.
2. install the thickest best quality filters available in your air circulation unit.
3. change your air filters often.
4. professionally clean your home ducts and AC unit (at least once).
5. replace carpets with hard floors.

Along with completing these tasks, adding room filters and/or whole house vacuums should help and also improve your state of mind. I highly recommend having the entire ducts and AC system cleaned professionally (#4) in a high rise condo such as in your photos.

 

[chirhone]

Yesterday I went around the city testing it in other condos a little farther from main road, but I measured the same 20 ug/m^3 at 32 floors and higher floors and 30+ ug/m^2 at lower floors. In other words, the pollution is uniform around the city, And today I read this headlines.

http://inqm.news/odix

"Air pollution from burning fossil fuels --- primarily coal, gas and oil --- is responsible for an estimated 27,000 premature deaths in the Philippines annually, and result in up to $6 billion (P304 billion) in economic losses per year, according to a new study released on Wednesday."

In your area, don't you have pollution? Doesn't it bother you? It can get into bloodstream and cause dementia later in life.

Before Christmas. I never thought pollution could even occur in the 32th floor. I thought pollution meant direct exposure to the street cars or living near chimneys of factories. In fact. I knew more about dark matter than pm2.5 particulate pollutions. I guess most in the public are not aware the haze can even reach you (like in 32th floor) where you are not directly in front of the vehicles.

I think the general public is more aware of dark matter than pm2.5 particulate pollutions, right?

 

[chemisttree]

In short. Pollution is higher at 4am to 10am or early morning and this is official and occur everywhere? We tend to think pollution is greater at mid day as there are more and more cars.

Well, perhaps not everywhere. The diurnal variability of PM2.5 is a known thing. The layer that I referred to in my previous post is described as the “planetary boundary layer” (PBL) in the referenced study. How that varies during the day is discussed on pages 8-10 and it is noted that the maximum concentration of PM2.5 is seen at dawn and the early morning hours for most of India during this time of year. This is mainly due to the diurnal variation in the PBL, its expansion during the day diluting the particles. It’s not true everywhere though.

 

[russ_watters]

But pm2.5 particles being 2.5 microns or less don't gravitate, so why don't they diffuse to the atmosphere above? I am still trying to confirm whether haze or mist is major portion of it so i can decide whether to buy an 60 sq. mtr air purifier...

I asked all this so i can know whether to buy an air purifier. Should I? I live in 32th floor. Look at the city picture. The sky is big. Why don't pm2.5 particulate diffuse away into the rest of atmosphere instead of getting in my unit at 32th floor?

2.5micron particles do "gravitate". The smaller the particle the more it behaves like a gas, but there is no firm cutoff where they no longer settle. A quick google tells me that the half life of 1 micron particles in a 2.5m high clean room with turbulent air have a half life for settling of 12 hours. That's pretty slow, but it is enough to say they won't disperse without help from the weather. A calm morning means no help. And when an inversion layer traps them (as others said), it's even worse.

So I don't see a conundrum here; believe your particle counters and get an air purifier.

 

[chemisttree]

And don’t forget. Some of these particles are sulfate aerosols which are known to adsorb moisture in the air when the relative humidity is high. Kind of like an inverted jelly roll. When this happens the particle size grows and it is these water-swollen particles that contribute to the increased scattering of the shorter wavelength light at dawn. The blues from the early morning sky provides a uniform source and scattering is fairly pronounced. Later in the day when the RH drops, these particles dry out and shrink down in size. The smaller sizes aren’t efficient scatterers and the air appears to clear up. Of course you know you can still read them on your meter.

 

[berkeman]

Sounds like the OP has been getting good advice. This is a good time to close the thread. Thanks everybody for helping the OP out.